For students taking Chemistry 101 at the University of Victoria in the Fall 2013 term.

Wednesday, September 4, 2013

Chapter 1

Any questions on Chapter 1 material? Ask them here.

138 comments:

Anonymous
said...

hello， I am try to know how to use the masteringchemistry to take the online quizzes. So, what should i do is to log in to take the test? Do I need the course ID ?what is that?

I enetered the course ID: MCCHEMISTRY83520 that I found on the uvic chemistry 101 page but mastering chemistry said "The Course ID you entered is closed for enrollment. Please contact the course instructor." So I guess that's what I'm doing now :) Anyways, I'll check back in a bit and hopefully there'll be an answer Thanks again for creating this blog!

Thank you both for the feedback. I checked with the course coordinator, and he tells me that the course has not been opened for access yet, but will be by the weekend.

Yes - your textbook! The lecture book sections match exactly with those in the textbook, so you should read the corresponding section before (or after) the lecture. I generally go through about 2 pages (4 slides) worth of material per 50 min class.

i logged onto the mastering chemistry site by putting a V in front of the course ID previously posted and it worked. But now im just hoping that it is the correct Course ID and the right dates

Mastering Chemistry was opened for access late Friday morning September 6th. The course ID is on page viii of the lecture notebook and here http://web.uvic.ca/~chem101/mastering.html

Will we be going over any of the questions from the Practice quiz in class or is it just to get use to using the program? As well, where do i find the 'Mastering Chemistry Exercise

1051: The practice quiz is just to show you how to use MasteringChemistry. 144: Your question seems to be incomplete. We will be going over MasteringChemistry questions this week in class.

Is there anywhere on the Mastering Chemistry site that tells us what pages we should read from the textbook or the other Chemistry 101 notebook? Suppose we wanted to read the information that would be contained in a lecture before the day of that lecture, or if we wanted to know what pages to read before attempting homework or quizzes. IS there anywhere on the site that would give us this information?

1210: I don't *think* UVic uses iclicker>GO - there is some resistance to the idea of having people getting out their smartphones multiple times during lectures - but I will make some inquiries. Note that clickers are used in some 2nd year classes, so the savings may not be as substantial as you hope.

1245: If you want to read ahead, I very much encourage you to do so. The lecture book sections match exactly with those in the textbook, so you should read the corresponding section before (or after) the lecture. I generally go through about 2 pages (4 slides) worth of material per 50 min class.

On the website it says the only calculator permitted for this course is the Sharp EL-510R, however the bookstore sells and advertises the Sharp EL-510RN, is the calculator acceptable to use for exams?

I registered my code for the textbook earlier but did not download it, and now Pearson is not letting me log in to access it. I have verified that my login name and password are correct, but it keeps rejecting them. I don't know if I did something wrong or if it is a problem with the system, but I can't access the textbook or Mastering Chemistry.

Hi, I tried the practice quiz from the computers in the McPherson library and had a really hard time reading the questions. Some words in the sentences overlap making them very difficult to read and the symbols aren't displaying (eg. "(\(\texttip{\nu }{nu}\))"). I wanted to look through the homework assignment instead but I'll lose out on the quiz info if I open another assignment. Since the quiz isn't worth marks at this point, I'll just open the assignement and lose the quiz, but is there a way to go back and review the material?

851: the Sharp EL-510RN must be Ok if it is the one the library sells. 952: You will need to contact MasteringChemistry help. 253: Hmm, interesting; what browser are they using? Try contacting MasteringChemistry help and send them a screenshot of the peculiar rendering.

How do assignments work for this class? I see that they are posted on MasteringChemistry. Do we complete them online on MasteringChemistry, or do we hand in paper assignments in class?

I noticed that on the lab schedule it shows the same lab experiment 2 weeks in a row, do we work on the same lab 2 weeks in a row or do we only have to attend one?

I was wondering about the practice quiz. On the weekend, we got an email from Prof. Briggs saying that we needed to do the Intro to Mastering Chemistry and the practice quiz to test links and what not. I did the Intro fine, and the quiz which I did poorly on since I didn't know the material as well as I could have. But since I was told to do it, without needed previous knowledge, I did. However, yesterday in lecture (1:00-2:20), you said for us not to do the practice quiz yet since we would do badly (as I did). I wanted to clarify that the quiz is not for marks, and was also wondering if it will a disadvantage if we already did the quiz without first having had the lectures.

1046: You don't hand in any assignments; you complete them all online. 1138: Attend one. Odd-numbered lab sections come in this week, even come in the next week. 728: The practice quiz is not for marks. Don't do the 1st quiz - if you've done it already, contact Dr Briggs and ask him to reset it for you. Basically: you need to remember to do the quiz, but you disadvantage yourself by doing it before we've covered the necessary material. We will go over MC in class on Wed/Thur.

This question isn't on the chapter, but rather for lab spaces for Chem 102, there are a couple spaces available but when I try to join it doesn't allow me to, saying the section is "closed". and when I try to waitlist myself for full lab sections it doesn't let me do that either. Should i just keep regularly checking for spaces and to see if it works next time? or is this a system error that shouldn't be occuring? I am enrolled in Chem 102 lecture, but I'm trying to find an open lab space

I just want to clarify that odd lab courses are starting this week and even lab courses are starting next week. I just want to make sure that I don't miss my first lab! Also, do we have to have a flow chart and hazard table ready for our first lab? And do we need the hard backed laboratory notebook with the carbonless copies for the first lab? Thanks!

Hello， I don`t know how to use the MC to do the assignment like typing the number into the dialog box(cause I cannot type the numbers in the dialog box), so could you show us to use the MC in a detailed way in class. Thanku.

hello, I was doing some of the homework questions on mastering chemistry and one question said that "One type of sunburn occurs on exposure to UV light of wavelength in the vicinity of 300nm ." It then told me to calculate energy. My final answer was to 1 significant figure, as 300 only has 1 sig fig. The system marked it wrong and put the answer to 3 sig figs. The amount of sig figs was not specified by the question. What are we supposed to do in a situation like this on a quiz?

Hey there, I'm just wondering how we're supposed to know how many sig figs are used for what constants? For example, in your lecture book you gave the speed of light to 3 sig figs, whereas in the homework assignment they gave it to 4 sig figs. Will there be a sheet we can refer to for the sig figs of constants?

300 might have 3 s.f. or 1 s.f., it's an ambiguous case. The examples you see in exams will not be ambiguous. In cases where you're not sure (like this one), err on the side of more s.f.'s - I suggest using one of the other values in the calculation to help you decide. Base the number of s.f.'s ont he data you're given, so if the problem gives you 4, use 4; if it gives you 3, use 3, and so on.

Hello! So, practice quizzes and their adaptive follow up are not required to do and are not graded whereas graded quizzes and their follow ups are due and graded (or just the graded quizzes are due and graded?)

why is it that different elements have different line spectrums?

The equation for the change in energy only involves difference in whole number energy levels. Ex. an energy drop of 7 to 2.

So, what's stopping hydrogen from getting an electron excited to n=7 and then dropping to n=2, like any other element? If an electron in hydrogen got enough energy level, it could go up to n=7, right?

Because elements attract their electrons to varying degrees. Li for example has 3 protons and 3 electrons. So the nucleus of Li will attract those electrons more strongly than in H... but the electrons themselves screen (hide) some of the nuclear charge. So, it gets complicated fast! This manifests itself in line spectra that get increasingly complicated. Nothing is stopping an electron in H getting excited to n = 7 then dropping to n = 2; indeed, this is one of the lines in the Balmer series... but it's just slightly too high in frequency to appear in the visible region (it's at 397 nm, in the UV). So we see 3->2, 4->2, 5->2 and 6->2... but not 7->2. A UV detector would see it. As would a mantis shrimp.

If an atom of hydrogen were to encounter a photon of light which was inbetween the required energy states from n=2 and n=3, what would happen? Would the photon just not be absorbed, or would the electron absorb it and be promoted to n=2? If this promotion happens, how is energy conserved?

If you remember from last class we were explaining the uncertainty principle via Schrodinger's Cat. There is a great video explaining this further. It will help get your mind wrapped around this concept.

If atoms can only absorb specific energies of waves, then how come in the photoelectric effect, a greater energy than the threshold can be absorbed...it's just that the electron will conserve the rest as Kinetic energy?

Perhaps the one exception is when enough energy is supplied to make n=infinity?

201: thanks, great link! I liked IDTIMWYTIM's video on Heisenberg's uncertainty principle, too. 455: Rydberg's equation doesn't work for other gases because they are complicated by the presence of other electrons. The equation does work (with a different constant) for other hydrogen-like systems such as He+ or Li++, but they're pretty exotic.

In the photoelectric effect, you're ionizing the metal and the excess energy can be dumped into the translational energy of the electron, which though quantized, is very finely so (i.e. the gaps between translational energy levels are very, very fine).

Can we expect the difficulty of the first graded quiz to be similar to that of the practice quiz? I found the practice quiz to be very difficult even though I've gone over the material we've learned multiple times...

I didn't realize we had to complete the quiz by 12:20pm this afternoon for some reason I had assumed that we would have until the end of the night to complete it so unfortunately I am now unable to complete the practice quiz. Since the quiz isn't for marks and is only for our practice is there anyway these deadlines will be extended so I can complete the practice quiz before the actual quiz on Wednesday to be sure I have an understanding of the lecture material?

To 10:55 The Practice Quiz is for practice. It doesn't contribute to your grade. It contains subject material that most students likely encountered in their Chem 11 or other prerequisite course(s). It is good to familiarize yourself with these concepts and calculations because they may well be useful soon in the lab part of the course, for example.

To 5:24 There are two Practice Quizzes. They are identical. They differ only by having different due dates. One due date has passed. It was September 15th. The other Practice Quiz has October 6th as its due date.If you have tried the one with the earlier due date, then the answers should now be available to you. If you want to do it again then do the one that has October 6 as its due date. After the due dates you can still access the Practice Quizzes but you can't actually do them because the answers become visible.

Graded Quiz #1 is due at midnight Wednesday September 18 (actually 11:59pm) The subject matter included is part of the title of every Graded Quiz.

There are several issues related to the use of iClickerGo software. Therefore it will not be enabled for Chem 101 at this time. 1. Using Iclicker Go requires that instructor and students sign up for an account with the vendor. Iclicker’s proposed terms of use and privacy policy for this service (attached) have yet to be reviewed, modified and approved by our UVic Privacy Office & Legal Counsel and then signed by Iclicker, so at this point all we have is their ‘draft’ promise that all student data will be stored on computer systems on Canadian soil. (This is important because of our Freedom of Information & Protection of Privacy Act.)

Likely the key thing here is for your students to be fully aware that they would need to provide a vendor with personal information in order to use Iclicker Go, and that at present neither UVic nor you have an official signed statement from the vendor to the effect that student data will only ever be stored on computer systems in Canada.

2. Although Iclicker Go is supposed to integrate into the physical system (base station + physical remotes + Iclicker software) seamlessly, and although votes submitted via Iclicker Go should show up in your polling results and in Igrader just as those submitted via dedicated remotes, Iclicker Go does everything over the internet, while the dedicated devices use radio frequency in the classroom. What this means is that you may notice a lag in the transmission of the votes submitted via Go.

One of the problems offered in the MasteringChemistry practice quiz adaptive follow up showed images of compounds and then asked for the molecular formula. These are some of the molecules: http://session.masteringchemistry.com/problemAsset/1257633/3/BLB10.2.46.jpg (I hope this link works) When writing this molecular formula, how do we know what order to put the elements in? For example, in the linked image, molecule "a" has 2 carbons, 1 bromine, and 5 hydrogens. The correct answer is C2H5Br. How do we know this is the correct order? Why is it not H5C2Br or BrC2H5 or some other combination? Thank you.

1242: You don't need to know this stuff for the quiz, but yes, there is method to the madness! Chemists always put C first, H second, then all the rest of the elements alphabetically. 208: Yes, you have if you are in section A01 and A02. If you're in A03, you have if you have completed section 1.3 in class. 259: No. No (but you should, at least to check that you are as on top of the material as you think you are!)

The issue of writing formulas and what is connected to what: If we are writing a molecular formula then De McIndoe has given the convention for this. If we mean to imply connectivity, then there are other conventions. For the formula C2H2Br there is only one pattern of connectivity, so it doesn't matter how you write them. If an atom is followed by a second atom that has a counting subscript, sich as CH3, then the convention is that three H atoms are separately connected to that carbon atom. The fourth bond from that carbon is connected to the next atom listed in the string. An exception arises for the classical strong acids such as HNO3 and H2SO4. In such acids, the leading H is not directly attached to N or S. If we ask you to draw a Lewis structure (eventually) then we will inform you of the pattern of connectivity if there is ambiguity.

I am unable to complete the practice quiz that was "due" yesterday (i.e. the first question is regarding wavelength)- and unable to see the answers - although it is different from the one that is still open to complete on MasteringChemistry (i.e. beginning with questions on Avogadro's number).

Would it be possible to re-open the first practice quiz and/or post the answers? Thanks!

The practice quizzes contained a lot of chem 11 and 12 questions. Is the graded quiz just what we have learned so far in the course or does it also contain chem 11 and 12 questions?

When i was checking my work over for question 3 with the video problem solving, she uses -3.29x10^15 s (1/nf - 1/ni), while in my notes i have -2.18x10^-18 J (1/nf - 1/ni). Can you explain how they got to that number?

People in labs, do we need to do our hazard table and flow charts on the notebook we have or just normal looseleaf? Also these are due every lab corresponding to the experiment we are doing in the lab correct?

When do we use the Rydberg Equation and the Bohr Equation? Do we have to know the Rydberg Equation because it is not in our notes but in our assignment?

The first question for chapter 1 in the class notebook is about photodissociation of O2. The question gives Î”H which is later used as the energy. We have seen the equation Î»=hc/E in class. In the online solution video, the equation used is Î»=hc/Î”H.

Are Î”H and E the same thing? What is H? The question just gives a value and its units without explicitly saying what it is. Will energy be written as E or Î”H in quizzes/exams?

Hello, The due date for assignment 1 is Sunday Sept 22. In class we have only covered up to the end of section 1.4, so we have 4 more sections remaining... Even if we finish chapter 1 in class on Thursday (which seems unlikely at the pace we are going), this leaves very little time to do the homework questions after seeing the material in class. I realize that the homework assignments are not for marks, but will they still be accessible after Sunday? Is there anyway this due date could be extended to give us more time to do them?

Remember, Î”H is enthalpy change, but that is really just energy added or removed from the system in KJ per mol. Hence why it can be easily divided by avagodros number and be converted into energy.

When I was doing the practice quiz on mastering chemistry, there were two times when I had the answer right but it didn't accept it and said, "One attempt left. Try again." Will this happen during the real quiz? Does it mean that I need a better internet connection?

756: See Dr Briggs' response earlier regarding due dates of quizzes. 810: Rydberg/Bohr etc - they're all basically the same equation, so you can use one to solve for e.g. E then determine wavelength since E = hc/lambda. Same for frequency, etc. 812: see 848 826: see my answer to 756 849: It shouldn't. Maybe. Did you have a bad connection? 949: Yes 956: Ha! Yes, you're right

I read your response to 826 which said to see Sandy Brigg's comment. Sandy's comment is regarding quizzes, not homework. Will we still be able to access the homework assignments after their due date? Homework assignment 1 is due Sunday and that is not much time after we finish the chapter material this week to do the questions (if we finish the chapter material).

On the graded quiz, will there only be questions on material we've learned so far in this course or will there also be questions about the chem 11 calculations that took up the majority of the practice quiz?

On the graded quiz, will there only be questions on material we've learned so far in this course or will there also be questions about the chem 11 calculations that took up the majority of the practice quiz?

1102, 1110: The quiz is mostly on sections 1.1-1.3 of your notes/textbook. Chem101 does presuppose knowledge from Chem11, but we do not examine it explicitly (except perhaps in lab work).

There are about 926 students registered in Chemistry 101. There are 849 students signed up in Mastering Chemistry. So the 77 students not signed up will have to hurry, as Graded Quiz #1 us due tonight at 11:59pm.

Also, the Course ID for Mastering Chemistry is on page viii of the Lecture Notebook and on the Mastering Chemistry page of the course web site. The personal access code is included in your textbook package that you purchased from the Bookstore on campus.

does the 2S orbital include the 1S orbital inside of it? or is the 2S orbital a big sphere with a whole inside?

Can electrons in the 2S orbital occupy space in the 1S orbital?

For example, look at the middle of figure 1.21 in the text. it seems as though the graph for the 2s orbital has the 1s orbital included inside of it, but with the possibility of finding the electron further from the radius

They actually occupy some of the same space, but the 2s electron on average spends more of its time further away from the nucleus than the 1s electron.

But if you look at the graph in figure 1.21 of the text, it seems like the density of the 2S orbital is still highest where the 1S is highest. This would mean that no matter which orbital you're in (1s, 2s, 3d), the chances of finding the electron is still greatest at the core?

Is there any way that you can change your answer for a question on the online quiz? because I submitted an answer, but then I realized that I had done it wrong and figured out the correct answer.

Do we need to know how many nodes are in the p or d orbitals? How would we be able see how many nodes are in orbitals that are not spheres? Also, do we need to know how the different p orbitals overlap eachother? Much like the S orbitals all build on one another?

In the pictures of the 1s, 2s, 3s orbitals on page 21, it looks as if in the 2s orbital, the 1s is inside of it. Is this the case? Is the 1s orbital, in a way, part of the 2s? And then in the 3s orbital, the 2s orbital is inside?

547: Yes, all s orbitals have their maximum electron density at the nucleus (not true for other orbitals, all of which have a node at the nucleus). However, that's not to say that the chances of finding the electron are highest there! The electron spends most of its time well away from the nucleus, and increasingly so as the principal quantum number increases. 716: once the quiz closes, after midnight 746: no 753: yes. All orbitals have n=1 nodes, and s, p, d and f orbitals have 0, 1, 2 and 3 angular nodes each. The p orbitals minimize their overlap, which is why they're all orthogonal to each other. 807: the orbitals all overlap each other to a greater or lesser extent, yes. However, imagine a 1s electron in a heavy atom - it is being attracted *very* strongly to the nucleus, so effectively spends its time much closer in than all the other electrons.

Possibly interesting video about the electron, the wave function, and Schroedinger's cat http://www.scientificamerican.com/video.cfm?id=what-is-the-wave-function---instant2013-09-19

The chapter 1 homework is due tomorrow night, but we have not even finished chapter 1 in class yet. Is there any way that this assignment deadline could be extended to give us more time to do the questions? I think this is a fair request because the homework is not for marks and we have not finished the chapter yet. Thank you.

For subshells that have 3 orbitals such as the P subshell, are we supposed to know which magnetic quantum numbers correspond to which orbitals? Ex, if we are talking about the P subshell then m=-1,0,1. And there is a Py, Px, Py orbitals. Do we need to know which numbers correspond to what orbitals? If so, is this in the book?

315: I believe Dr Briggs will set the assignment again with a different due date so you can try it again, yes. 330: that detail is not taught nor is it examinable. 359: it is part of the 3rd shell, but is higher in energy than the 4s orbital. So the period number corresponds to the principal quantum number for s and p orbitals, but not for the d and f. 458: No, it's in the data sheet.

hello, I am currently attempting to do our first homework assignment on mastering chemistry. Does this count towards a graded mark, or is it a completion mark? Also, as I have been completing the assignment, I seem to be getting quite a few questions incorrect due to "incorrect rounding". I have not been rounding until my final answer, and yet I get most questions wrong by .1 of a number. Will this affect my mark? Thanks.

Homework assignment 1 asks this question: List a possible set of four quantum numbers (n, â„“, mâ„“, ms) in order, for the highest energy electron in gallium, Ga. Refer to the periodic table as necessary. (Quantum Numbers and Electron Identification)

One of the hints for this question asks: In which principal energy level is the highest energy electron in Ga found? How do we determine which principal energy level the highest energy electron is found in?

Hello, could you please explain how to solve this sort of problem:

Write the condensed electron configurations for the following atoms, using the appropriate noble-gas core abbreviations. Se: Express your answer in condensed form in order of increasing orbital energy as a string without blank space between orbitals. For example, [He]2s22p2 should be entered as [He]2s^22p^2.

This is a Mastering Chemistry assignment 1 question. The answer given is [Ar]4s^23d^104p^4

1. First notice that Argon is the noble gas that precedes Selenium in the periodic table. Argon has 18 electrons. Use this as your base and get the rest of the electrons (16) from the other subshells. Move to the next row of elements in the periodic table.

2. Get 2 electrons from the 4th s-block, which has one orbital.

3. From the 3rd d-block we get 10 electrons from the 5 orbitals.

4. From the 4th p-block, which Selenium is in, we get the remaining 4 electrons (max is 6 for p-subshells because they have 3 orbitals)

5.This then get us the remaining 16 electrons we need to make Selenium. We then write this as [Ar]4s^23d^104p^4

I just follow the periodic table and compare it to the colored table on pg 16 in our notebook. That's just the method I use to get the formula. Hope this helps :)

848: The Highest energy electron will be found in the highest energy orbital, which is the last orbital to have electrons placed in it when doing your electron configuration.

For questions 7 and 9 in the lecture book (at the end of Ch. 1), when scanning these questions to get the solution, it takes you to organic chem material. Both questions 7 and 9 go to the same organic chem solution?

900: see 1121 1121: Nice one! Thanks, that's a pretty good summary. 1258: U has an anomalous electron configuration. We don't expect you to predict these. 1025: Aw, that's annoying, sorry. My mistake. You can find the correct ones at this page.

24 September 2013 Mastering Chemistry - There's now an extra copy of Homework Assignment 1 on Chapter 1. It is identical to the original Homework Assignment 1 but it has a due date of October 13. Students who have not attempted all or part of the original Homework Assignment 1 can now go and complete the extra copy in the usual way.

Further note re Mastering Chemistry - However, this new extra copy is largely unnecessary. The settings within Mastering Chemistry that are applied to the Homework Assignments are 1) Allow students to re-work for practice and 2) Do not penalize students for late submission. The effect of these settings is as follows. Students who attempt questions within a Homework Assignment before the due date will be able to see the correct answers and to re-work the questions ONLY after the due date. Students who first access the Homework Assignment after its due date will immediately be able to work the assignment and to see the correct answers. This is why the new copy of the Homework Assignment 1 is unnecessary. But it's there, so I'll leave it.

Hi for the Chapter 1 questions at the end of our notes, for #3 on the youtube video it says to use a number of -3.29 x 10^15 to find part b and I'm not sure where that number is coming from?

The last question on the quiz (due last night) was regarding molybdenum, which apparently has an irregular electron configuration. When we discussed this in class, you said that we didn't need to know the irregular configurations, so I assumed that molybdenum was regular... and I got that question wrong.

I'm just wondering if you can clarify whether or not we do need to know the irregular configurations? Thanks.

607: because the equation is for frequency and not wavelength, it uses the Rydberg constant multiplied by the speed of light. 747: You will see exactly what a midterm looks like, since we will be having a review session before the first midterm. They are likely to be somewhat different, since the quizzes are open-book and the midterms are not. 142: We don't expect you to memorize these, no. However, for open-book exams, we do expect you to be able to look up this information. Mo is anomalous for the same reason as Cr. You won't get a question like that in the midterms or final exam.

Sure. It's basically saying what values of l allow you to attain an ml value of 2. Well, since ml can take all the values -l...0...+l, you can only get to a value of ml = 2 for orbitals with l values of at least 2. So this is l = 2 or 3 (d and f orbitals). Technically, it would also be true for even higher l value orbitals, but chemists only worry about the s, p, d, and f, because these are the only ones typically encountered.

I'm looking at a picture on page 6 of the chem101 notebook (the one with all of the colourful arrows) and it shows a bunch of pink arrows, a bunch of green arrows then a bunch of red arrows. Does that mean an electron in hydrogen jumping from n=5 to n=1 will emit the same colour light as an electron jumping from n=3 to n=1? Thanks!

Will we be expected to identify different types of electromagnetic radiation based on their corresponding wavelengths/frequencies on the midterm? If so, will we be given an electromagnetic spectrum or must be memorize it?

We're not big on getting you to memorize stuff that is easy to just look up. Nonetheless, I would expect you to know SOME of this; for example, that UV light is more energetic than blue light and IR less so than red light (after all, there are clues in the names). I'm not terribly fussed about whether you remember that microwaves are shorter than radiowaves, though.

For the radial probability function, it seems that the peaks are around the middle of the orbital. For example, the 2p orbital ranges from about 0-7 angstroms but the optimum is at about 2....

With radial probability we multiply by the area, so it makes sense that we need to find this "maximum" between density and area.

However, i was wondering about the density graph... If we look at the 2s orbital, and we only look at the function between the 1st and 2nd node...does density increase as you get farther from the nucleus? the figure on page 9 of your notebook draws the darkest around the edges of the orbital.

However, for the 1s orbital, the density seems to decrease as you get farther.......

So, does density always start the largest right after the node, or is a maximum somewhere in the middle? Remember, we're talking about density here not radial probability

Check out the Orbitron. And note that for radial probability, you're multiplying by volume, not area (I know the analogy I used in class - London - was for area not volume, but I don't know a good volume analogy!).

One of the textbook questions is: calculate the uncertainty in the position of a 1.50-mg mosquito moving at a speed of 1.40m/s if the speed is known to within +/- 0.01m/s. How would you solve this because I keep getting the wrong number but the correct power and there is no explanation in the answer key?

903: Hard to comment without knowing more detail. Have you converted mg to kg? Ignored 1.4 m/s and just used 0.01 m/s? The answer ought to be delta x = h/4*pi*1.5*10-6*0.01. 906: you need to know the shapes, and that the labels tell you something about orientation. px orbitals point along the x axis. dxy lies in xy plane. dz2 points along z axis.

They're basically the same. angular = planar (these differentiate between different l values) radial = spherical (differentiate between different n value orbitals)

Should we memorize the Rydberg equation and Rydberg constant for the final? Because in the formula sheet at the back of the lecture notebook, they are not present.

One of the mastering chemistry questions is "when light of wavelength 630nm is directed onto the photocell, electrons are emitted at the rate of 2.6×10−12C/s . Assume that each photon that impinges on the photocell emits one electron. How many photons per second are striking the photocell? How much energy per second is the photocell absorbing?" I am totally stuck.

## 138 comments:

hello， I am try to know how to use the masteringchemistry to take the online quizzes. So, what should i do is to log in to take the test? Do I need the course ID ?what is that?

I enetered the course ID: MCCHEMISTRY83520 that I found on the uvic chemistry 101 page but mastering chemistry said "The Course ID you entered is closed for enrollment. Please contact the course instructor."

So I guess that's what I'm doing now :)

Anyways, I'll check back in a bit and hopefully there'll be an answer

Thanks again for creating this blog!

Thank you both for the feedback. I checked with the course coordinator, and he tells me that the course has not been opened for access yet, but will be by the weekend.

Is there a place to find assigned or suggested readings for each lecture?

Yes - your textbook! The lecture book sections match exactly with those in the textbook, so you should read the corresponding section before (or after) the lecture. I generally go through about 2 pages (4 slides) worth of material per 50 min class.

i logged onto the mastering chemistry site by putting a V in front of the course ID previously posted and it worked. But now im just hoping that it is the correct Course ID and the right dates

Do you mean you entered VMCCHEMISTRY83520?

For those of us that are still on the waitlist, how do we gain access to moodle?

There is no Moodle for this course.

The course ID is on page viii of the lecture notebook and here

http://web.uvic.ca/~chem101/mastering.html

Sandy Briggs

Course Coordinator

Mastering Chemistry was opened for access late Friday morning September 6th.

The course ID is on page viii of the lecture notebook and here

http://web.uvic.ca/~chem101/mastering.html

Sandy Briggs

Course Coordinator

Is the first practice quiz on MasteringChemistry based on knowledge we should already have?

Will we be going over any of the questions from the Practice quiz in class or is it just to get use to using the program? As well, where do i find the 'Mastering Chemistry Exercise

1051: The practice quiz is just to show you how to use MasteringChemistry.

144: Your question seems to be incomplete.

We will be going over MasteringChemistry questions this week in class.

Can we use the "iClicker GO" version of iClicker? It's considerably less expensive than buying the actual device.

Is there anywhere on the Mastering Chemistry site that tells us what pages we should read from the textbook or the other Chemistry 101 notebook? Suppose we wanted to read the information that would be contained in a lecture before the day of that lecture, or if we wanted to know what pages to read before attempting homework or quizzes. IS there anywhere on the site that would give us this information?

1210: I don't *think* UVic uses iclicker>GO - there is some resistance to the idea of having people getting out their smartphones multiple times during lectures - but I will make some inquiries. Note that clickers are used in some 2nd year classes, so the savings may not be as substantial as you hope.

1245: If you want to read ahead, I very much encourage you to do so. The lecture book sections match exactly with those in the textbook, so you should read the corresponding section before (or after) the lecture. I generally go through about 2 pages (4 slides) worth of material per 50 min class.

When you say 2 pages worth of material, are you referring to 2 pages in the textbook or lecture notebook?

The lecture book (hence the "4 slides" reference; you'll notice the slides correspond exactly to your lecture book).

On the website it says the only calculator permitted for this course is the Sharp EL-510R, however the bookstore sells and advertises the Sharp EL-510RN, is the calculator acceptable to use for exams?

I registered my code for the textbook earlier but did not download it, and now Pearson is not letting me log in to access it. I have verified that my login name and password are correct, but it keeps rejecting them. I don't know if I did something wrong or if it is a problem with the system, but I can't access the textbook or Mastering Chemistry.

Hi,

I tried the practice quiz from the computers in the McPherson library and had a really hard time reading the questions. Some words in the sentences overlap making them very difficult to read and the symbols aren't displaying (eg. "(\(\texttip{\nu }{nu}\))"). I wanted to look through the homework assignment instead but I'll lose out on the quiz info if I open another assignment. Since the quiz isn't worth marks at this point, I'll just open the assignement and lose the quiz, but is there a way to go back and review the material?

851: the Sharp EL-510RN must be Ok if it is the one the library sells.

952: You will need to contact MasteringChemistry help.

253: Hmm, interesting; what browser are they using? Try contacting MasteringChemistry help and send them a screenshot of the peculiar rendering.

How do assignments work for this class? I see that they are posted on MasteringChemistry. Do we complete them online on MasteringChemistry, or do we hand in paper assignments in class?

I noticed that on the lab schedule it shows the same lab experiment 2 weeks in a row, do we work on the same lab 2 weeks in a row or do we only have to attend one?

Hi,

I was wondering about the practice quiz. On the weekend, we got an email from Prof. Briggs saying that we needed to do the Intro to Mastering Chemistry and the practice quiz to test links and what not. I did the Intro fine, and the quiz which I did poorly on since I didn't know the material as well as I could have. But since I was told to do it, without needed previous knowledge, I did. However, yesterday in lecture (1:00-2:20), you said for us not to do the practice quiz yet since we would do badly (as I did). I wanted to clarify that the quiz is not for marks, and was also wondering if it will a disadvantage if we already did the quiz without first having had the lectures.

Thank you

1046: You don't hand in any assignments; you complete them all online.

1138: Attend one. Odd-numbered lab sections come in this week, even come in the next week.

728: The practice quiz is not for marks. Don't do the 1st quiz - if you've done it already, contact Dr Briggs and ask him to reset it for you. Basically: you need to remember to do the quiz, but you disadvantage yourself by doing it before we've covered the necessary material. We will go over MC in class on Wed/Thur.

This question isn't on the chapter, but rather for lab spaces for Chem 102, there are a couple spaces available but when I try to join it doesn't allow me to, saying the section is "closed". and when I try to waitlist myself for full lab sections it doesn't let me do that either. Should i just keep regularly checking for spaces and to see if it works next time? or is this a system error that shouldn't be occuring? I am enrolled in Chem 102 lecture, but I'm trying to find an open lab space

I just want to clarify that odd lab courses are starting this week and even lab courses are starting next week. I just want to make sure that I don't miss my first lab! Also, do we have to have a flow chart and hazard table ready for our first lab? And do we need the hard backed laboratory notebook with the carbonless copies for the first lab? Thanks!

Odd labs start THIS WEEK. You do not need a hazard table or flow chart for your first lab, but you are required to have the carbon paper booklet.

Hello， I don`t know how to use the MC to do the assignment like typing the number into the dialog box(cause I cannot type the numbers in the dialog box), so could you show us to use the MC in a detailed way in class.

Thanku.

930: contact Monica Reimer for lab-relatde questions.

112: 434 is correct

731: MC tutorial in class Wed and Thur

hello,

I was doing some of the homework questions on mastering chemistry and one question said that "One type of sunburn occurs on exposure to UV light of wavelength in the vicinity of 300nm ." It then told me to calculate energy. My final answer was to 1 significant figure, as 300 only has 1 sig fig. The system marked it wrong and put the answer to 3 sig figs. The amount of sig figs was not specified by the question.

What are we supposed to do in a situation like this on a quiz?

Hey there,

I'm just wondering how we're supposed to know how many sig figs are used for what constants? For example, in your lecture book you gave the speed of light to 3 sig figs, whereas in the homework assignment they gave it to 4 sig figs.

Will there be a sheet we can refer to for the sig figs of constants?

300 might have 3 s.f. or 1 s.f., it's an ambiguous case. The examples you see in exams will not be ambiguous. In cases where you're not sure (like this one), err on the side of more s.f.'s - I suggest using one of the other values in the calculation to help you decide.

Base the number of s.f.'s ont he data you're given, so if the problem gives you 4, use 4; if it gives you 3, use 3, and so on.

Hello!

So, practice quizzes and their adaptive follow up are not required to do and are not graded whereas graded quizzes and their follow ups are due and graded (or just the graded quizzes are due and graded?)

Thanks

Only graded quizzes count towards your final grade.

why is it that different elements have different line spectrums?

The equation for the change in energy only involves difference in whole number energy levels. Ex. an energy drop of 7 to 2.

So, what's stopping hydrogen from getting an electron excited to n=7 and then dropping to n=2, like any other element? If an electron in hydrogen got enough energy level, it could go up to n=7, right?

Because elements attract their electrons to varying degrees. Li for example has 3 protons and 3 electrons. So the nucleus of Li will attract those electrons more strongly than in H... but the electrons themselves screen (hide) some of the nuclear charge. So, it gets complicated fast! This manifests itself in line spectra that get increasingly complicated.

Nothing is stopping an electron in H getting excited to n = 7 then dropping to n = 2; indeed, this is one of the lines in the Balmer series... but it's just slightly too high in frequency to appear in the visible region (it's at 397 nm, in the UV). So we see 3->2, 4->2, 5->2 and 6->2... but not 7->2. A UV detector would see it. As would a mantis shrimp.

[mantis shrimp]

Are we going to given constants(ie Planck's or Rydberg's) in during midterms or finals along with a formula sheet?

The data sheet you get in exams appears on the inside back cover of your lecture book.

If an atom of hydrogen were to encounter a photon of light which was inbetween the required energy states from n=2 and n=3, what would happen? Would the photon just not be absorbed, or would the electron absorb it and be promoted to n=2? If this promotion happens, how is energy conserved?

The photon would not be absorbed.

If you remember from last class we were explaining the uncertainty principle via Schrodinger's Cat. There is a great video explaining this further. It will help get your mind wrapped around this concept.

For anyone who is curious, feel free to watch :)

http://www.youtube.com/watch?v=uWMTOrux0LM

Why can't Rydberg's equation be used for other gasses?

If atoms can only absorb specific energies of waves, then how come in the photoelectric effect, a greater energy than the threshold can be absorbed...it's just that the electron will conserve the rest as Kinetic energy?

Perhaps the one exception is when enough energy is supplied to make n=infinity?

201: thanks, great link! I liked IDTIMWYTIM's video on Heisenberg's uncertainty principle, too.

455: Rydberg's equation doesn't work for other gases because they are complicated by the presence of other electrons. The equation does work (with a different constant) for other hydrogen-like systems such as He+ or Li++, but they're pretty exotic.

In the photoelectric effect, you're ionizing the metal and the excess energy can be dumped into the translational energy of the electron, which though quantized, is very finely so (i.e. the gaps between translational energy levels are very, very fine).

Hello! Can we only take practice quizzes once or is there a way of doing them again?

Can we expect the difficulty of the first graded quiz to be similar to that of the practice quiz? I found the practice quiz to be very difficult even though I've gone over the material we've learned multiple times...

I didn't realize we had to complete the quiz by 12:20pm this afternoon for some reason I had assumed that we would have until the end of the night to complete it so unfortunately I am now unable to complete the practice quiz. Since the quiz isn't for marks and is only for our practice is there anyway these deadlines will be extended so I can complete the practice quiz before the actual quiz on Wednesday to be sure I have an understanding of the lecture material?

524, 1055, 827: I've asked Dr Briggs to comment on these queries. Please check back later today.

To 10:55 The Practice Quiz is for practice. It doesn't contribute to your grade. It contains subject material that most students likely encountered in their Chem 11 or other prerequisite course(s). It is good to familiarize yourself with these concepts and calculations because they may well be useful soon in the lab part of the course, for example.

To 5:24 There are two Practice Quizzes. They are identical. They differ only by having different due dates. One due date has passed. It was September 15th. The other Practice Quiz has October 6th as its due date.If you have tried the one with the earlier due date, then the answers should now be available to you. If you want to do it again then do the one that has October 6 as its due date. After the due dates you can still access the Practice Quizzes but you can't actually do them because the answers become visible.

Graded Quiz #1 is due at midnight Wednesday September 18 (actually 11:59pm) The subject matter included is part of the title of every Graded Quiz.

There are several issues related to the use of iClickerGo software. Therefore it will not be enabled for Chem 101 at this time. 1. Using Iclicker Go requires that instructor and students sign up for an account with the vendor. Iclicker’s proposed terms of use and privacy policy for this service (attached) have yet to be reviewed, modified and approved by our UVic Privacy Office & Legal Counsel and then signed by Iclicker, so at this point all we have is their ‘draft’ promise that all student data will be stored on computer systems on Canadian soil. (This is important because of our Freedom of Information & Protection of Privacy Act.)

Likely the key thing here is for your students to be fully aware that they would need to provide a vendor with personal information in order to use Iclicker Go, and that at present neither UVic nor you have an official signed statement from the vendor to the effect that student data will only ever be stored on computer systems in Canada.

2. Although Iclicker Go is supposed to integrate into the physical system (base station + physical remotes + Iclicker software) seamlessly, and although votes submitted via Iclicker Go should show up in your polling results and in Igrader just as those submitted via dedicated remotes, Iclicker Go does everything over the internet, while the dedicated devices use radio frequency in the classroom. What this means is that you may notice a lag in the transmission of the votes submitted via Go.

One of the problems offered in the MasteringChemistry practice quiz adaptive follow up showed images of compounds and then asked for the molecular formula.

These are some of the molecules:

http://session.masteringchemistry.com/problemAsset/1257633/3/BLB10.2.46.jpg (I hope this link works)

When writing this molecular formula, how do we know what order to put the elements in?

For example, in the linked image, molecule "a" has 2 carbons, 1 bromine, and 5 hydrogens. The correct answer is C2H5Br. How do we know this is the correct order? Why is it not H5C2Br or BrC2H5 or some other combination?

Thank you.

Have we covered everything we need to know for the graded quiz that is due this wednesday the 18th?

Are the homework assignments for marks? Do we have to do them?

1242: You don't need to know this stuff for the quiz, but yes, there is method to the madness! Chemists always put C first, H second, then all the rest of the elements alphabetically.

208: Yes, you have if you are in section A01 and A02. If you're in A03, you have if you have completed section 1.3 in class.

259: No. No (but you should, at least to check that you are as on top of the material as you think you are!)

To 12:42

The general convention used is to put the carbons first, followed by the hydrogens, then list the other elements in alphabetical order.

The issue of writing formulas and what is connected to what: If we are writing a molecular formula then De McIndoe has given the convention for this. If we mean to imply connectivity, then there are other conventions. For the formula C2H2Br there is only one pattern of connectivity, so it doesn't matter how you write them. If an atom is followed by a second atom that has a counting subscript, sich as CH3, then the convention is that three H atoms are separately connected to that carbon atom. The fourth bond from that carbon is connected to the next atom listed in the string. An exception arises for the classical strong acids such as HNO3 and H2SO4. In such acids, the leading H is not directly attached to N or S. If we ask you to draw a Lewis structure (eventually) then we will inform you of the pattern of connectivity if there is ambiguity.

I am unable to complete the practice quiz that was "due" yesterday (i.e. the first question is regarding wavelength)- and unable to see the answers - although it is different from the one that is still open to complete on MasteringChemistry (i.e. beginning with questions on Avogadro's number).

Would it be possible to re-open the first practice quiz and/or post the answers?

Thanks!

See Dr Briggs' answer above, posted at 937. Basically, do the one with the Oct 6 due date.

The practice quizzes contained a lot of chem 11 and 12 questions. Is the graded quiz just what we have learned so far in the course or does it also contain chem 11 and 12 questions?

Material from sections 1.1-1.3 mostly. We don't expect you to have completely forgotten Chem11 material, though.

When i was checking my work over for question 3 with the video problem solving, she uses -3.29x10^15 s (1/nf - 1/ni), while in my notes i have -2.18x10^-18 J (1/nf - 1/ni). Can you explain how they got to that number?

People in labs, do we need to do our hazard table and flow charts on the notebook we have or just normal looseleaf? Also these are due every lab corresponding to the experiment we are doing in the lab correct?

933: Krista is using the equation designed to find the frequency rather than the energy.

In the radial distribution probability graph, why does the peak get higher for each new S orbital?

Ex.. 10% chance of finding the electron at the peak of the 1s and 30% chance of finding it at the peak of the 2s.

Shouldnt the peaks be going down, but the graphs should be stretched out more for increases numbers of n?

429: Please let me know what figure you're looking at.

Did you leave extra practice quizzes with a new due date? Or are they for another specific quiz? They say extra copy.

When do we use the Rydberg Equation and the Bohr Equation? Do we have to know the Rydberg Equation because it is not in our notes but in our assignment?

The first question for chapter 1 in the class notebook is about photodissociation of O2. The question gives Î”H which is later used as the energy. We have seen the equation Î»=hc/E in class. In the online solution video, the equation used is Î»=hc/Î”H.

Are Î”H and E the same thing? What is H? The question just gives a value and its units without explicitly saying what it is. Will energy be written as E or Î”H in quizzes/exams?

Hello,

The due date for assignment 1 is Sunday Sept 22. In class we have only covered up to the end of section 1.4, so we have 4 more sections remaining... Even if we finish chapter 1 in class on Thursday (which seems unlikely at the pace we are going), this leaves very little time to do the homework questions after seeing the material in class. I realize that the homework assignments are not for marks, but will they still be accessible after Sunday? Is there anyway this due date could be extended to give us more time to do them?

Remember, Î”H is enthalpy change, but that is really just energy added or removed from the system in KJ per mol. Hence why it can be easily divided by avagodros number and be converted into energy.

When I was doing the practice quiz on mastering chemistry, there were two times when I had the answer right but it didn't accept it and said, "One attempt left. Try again." Will this happen during the real quiz? Does it mean that I need a better internet connection?

For the graded quizzes, are we allowed to look at our notes when writing it?

No, Mcindoe will strike you with his meter stick! I am sure you can.

756: See Dr Briggs' response earlier regarding due dates of quizzes.

810: Rydberg/Bohr etc - they're all basically the same equation, so you can use one to solve for e.g. E then determine wavelength since E = hc/lambda. Same for frequency, etc.

812: see 848

826: see my answer to 756

849: It shouldn't. Maybe. Did you have a bad connection?

949: Yes

956: Ha! Yes, you're right

I read your response to 826 which said to see Sandy Brigg's comment. Sandy's comment is regarding quizzes, not homework. Will we still be able to access the homework assignments after their due date? Homework assignment 1 is due Sunday and that is not much time after we finish the chapter material this week to do the questions (if we finish the chapter material).

Yes, the homework will be made available again later.

On the graded quiz, will there only be questions on material we've learned so far in this course or will there also be questions about the chem 11 calculations that took up the majority of the practice quiz?

On the graded quiz, will there only be questions on material we've learned so far in this course or will there also be questions about the chem 11 calculations that took up the majority of the practice quiz?

Mostly sections 1.1-1.3

Will we have to balance any chemical equations or compute any molar masses for quiz 1? Thank you.

Which types of skills and calculations from chemistry 11 will we need to know for the quiz? thanks

1102, 1110: The quiz is mostly on sections 1.1-1.3 of your notes/textbook. Chem101 does presuppose knowledge from Chem11, but we do not examine it explicitly (except perhaps in lab work).

I can't find my masteringchemistry access code. What page is it exactly in the textbook?

There are about 926 students registered in Chemistry 101. There are 849 students signed up in Mastering Chemistry. So the 77 students not signed up will have to hurry, as Graded Quiz #1 us due tonight at 11:59pm.

Also, the Course ID for Mastering Chemistry is on page viii of the Lecture Notebook and on the Mastering Chemistry page of the course web site. The personal access code is included in your textbook package that you purchased from the Bookstore on campus.

does the 2S orbital include the 1S orbital inside of it? or is the 2S orbital a big sphere with a whole inside?

Can electrons in the 2S orbital occupy space in the 1S orbital?

For example, look at the middle of figure 1.21 in the text. it seems as though the graph for the 2s orbital has the 1s orbital included inside of it, but with the possibility of finding the electron further from the radius

They actually occupy some of the same space, but the 2s electron on average spends more of its time further away from the nucleus than the 1s electron.

But if you look at the graph in figure 1.21 of the text, it seems like the density of the 2S orbital is still highest where the 1S is highest. This would mean that no matter which orbital you're in (1s, 2s, 3d), the chances of finding the electron is still greatest at the core?

When can we see our results from today's quiz?

Is there any way that you can change your answer for a question on the online quiz? because I submitted an answer, but then I realized that I had done it wrong and figured out the correct answer.

Do we need to know how many nodes are in the p or d orbitals?

How would we be able see how many nodes are in orbitals that are not spheres?

Also, do we need to know how the different p orbitals overlap eachother? Much like the S orbitals all build on one another?

In the pictures of the 1s, 2s, 3s orbitals on page 21, it looks as if in the 2s orbital, the 1s is inside of it. Is this the case? Is the 1s orbital, in a way, part of the 2s?

And then in the 3s orbital, the 2s orbital is inside?

^Not just "some overlap," but completely part of it, as shown in the pictures of page 21

547: Yes, all s orbitals have their maximum electron density at the nucleus (not true for other orbitals, all of which have a node at the nucleus). However, that's not to say that the chances of finding the electron are highest there! The electron spends most of its time well away from the nucleus, and increasingly so as the principal quantum number increases.

716: once the quiz closes, after midnight

746: no

753: yes. All orbitals have n=1 nodes, and s, p, d and f orbitals have 0, 1, 2 and 3 angular nodes each. The p orbitals minimize their overlap, which is why they're all orthogonal to each other.

807: the orbitals all overlap each other to a greater or lesser extent, yes. However, imagine a 1s electron in a heavy atom - it is being attracted *very* strongly to the nucleus, so effectively spends its time much closer in than all the other electrons.

Possibly interesting video about the electron, the wave function, and Schroedinger's cat http://www.scientificamerican.com/video.cfm?id=what-is-the-wave-function---instant2013-09-19

The chapter 1 homework is due tomorrow night, but we have not even finished chapter 1 in class yet. Is there any way that this assignment deadline could be extended to give us more time to do the questions? I think this is a fair request because the homework is not for marks and we have not finished the chapter yet.

Thank you.

For subshells that have 3 orbitals such as the P subshell, are we supposed to know which magnetic quantum numbers correspond to which orbitals? Ex, if we are talking about the P subshell then m=-1,0,1. And there is a Py, Px, Py orbitals. Do we need to know which numbers correspond to what orbitals? If so, is this in the book?

is the 3d orbital part of the third shell or 4th shell?

Recall that in your notes it says that period number is equal to the value of n.

So then since 3d is in the 4th period, would it be part of n=4, and thus the 4th shell?

do we need to memorize the Heisenberg's uncertainty principle formula?

315: I believe Dr Briggs will set the assignment again with a different due date so you can try it again, yes.

330: that detail is not taught nor is it examinable.

359: it is part of the 3rd shell, but is higher in energy than the 4s orbital. So the period number corresponds to the principal quantum number for s and p orbitals, but not for the d and f.

458: No, it's in the data sheet.

Are the assignments on Mastering Chemistry due for marks? If not, are we able to complete them after the assigned online due date?

649: No. Yes, they will be reassigned.

hello, I am currently attempting to do our first homework assignment on mastering chemistry. Does this count towards a graded mark, or is it a completion mark?

Also, as I have been completing the assignment, I seem to be getting quite a few questions incorrect due to "incorrect rounding". I have not been rounding until my final answer, and yet I get most questions wrong by .1 of a number. Will this affect my mark?

Thanks.

Homework assignment 1 asks this question:

List a possible set of four quantum numbers (n, â„“, mâ„“, ms) in order, for the highest energy electron in gallium, Ga. Refer to the periodic table as necessary.

(Quantum Numbers and Electron Identification)

One of the hints for this question asks: In which principal energy level is the highest energy electron in Ga found?

How do we determine which principal energy level the highest energy electron is found in?

Hello, could you please explain how to solve this sort of problem:

Write the condensed electron configurations for the following atoms, using the appropriate noble-gas core abbreviations.

Se:

Express your answer in condensed form in order of increasing orbital energy as a string without blank space between orbitals. For example, [He]2s22p2 should be entered as [He]2s^22p^2.

This is a Mastering Chemistry assignment 1 question. The answer given is [Ar]4s^23d^104p^4

Thank you

For the condensed electron configuration of Se:

1. First notice that Argon is the noble gas that precedes Selenium in the periodic table. Argon has 18 electrons. Use this as your base and get the rest of the electrons (16) from the other subshells.

Move to the next row of elements in the periodic table.

2. Get 2 electrons from the 4th s-block, which has one orbital.

3. From the 3rd d-block we get 10 electrons from the 5 orbitals.

4. From the 4th p-block, which Selenium is in, we get the remaining 4 electrons (max is 6 for p-subshells because they have 3 orbitals)

5.This then get us the remaining 16 electrons we need to make Selenium. We then write this as [Ar]4s^23d^104p^4

I just follow the periodic table and compare it to the colored table on pg 16 in our notebook. That's just the method I use to get the formula. Hope this helps :)

why is the electron configuration for Uranium [Rn] 7s2 6d1 5f3? not[Rn] 7s2 5f4?

848: The Highest energy electron will be found in the highest energy orbital, which is the last orbital to have electrons placed in it when doing your electron configuration.

For questions 7 and 9 in the lecture book (at the end of Ch. 1), when scanning these questions to get the solution, it takes you to organic chem material. Both questions 7 and 9 go to the same organic chem solution?

900: see 1121

1121: Nice one! Thanks, that's a pretty good summary.

1258: U has an anomalous electron configuration. We don't expect you to predict these.

1025: Aw, that's annoying, sorry. My mistake. You can find the correct ones at this page.

24 September 2013 Mastering Chemistry - There's now an extra copy of Homework Assignment 1 on Chapter 1. It is identical to the original Homework Assignment 1 but it has a due date of October 13. Students who have not attempted all or part of the original Homework Assignment 1 can now go and complete the extra copy in the usual way.

Further note re Mastering Chemistry - However, this new extra copy is largely unnecessary. The settings within Mastering Chemistry that are applied to the Homework Assignments are 1) Allow students to re-work for practice and 2) Do not penalize students for late submission. The effect of these settings is as follows. Students who attempt questions within a Homework Assignment before the due date will be able to see the correct answers and to re-work the questions ONLY after the due date. Students who first access the Homework Assignment after its due date will immediately be able to work the assignment and to see the correct answers. This is why the new copy of the Homework Assignment 1 is unnecessary. But it's there, so I'll leave it.

Hi for the Chapter 1 questions at the end of our notes, for #3 on the youtube video it says to use a number of -3.29 x 10^15 to find part b and I'm not sure where that number is coming from?

How similar in content and difficulty will the midterm be to the quizzes? thanks

Hi Dr. McIndoe,

The last question on the quiz (due last night) was regarding molybdenum, which apparently has an irregular electron configuration.

When we discussed this in class, you said that we didn't need to know the irregular configurations, so I assumed that molybdenum was regular... and I got that question wrong.

I'm just wondering if you can clarify whether or not we do need to know the irregular configurations?

Thanks.

607: because the equation is for frequency and not wavelength, it uses the Rydberg constant multiplied by the speed of light.

747: You will see exactly what a midterm looks like, since we will be having a review session before the first midterm. They are likely to be somewhat different, since the quizzes are open-book and the midterms are not.

142: We don't expect you to memorize these, no. However, for open-book exams, we do expect you to be able to look up this information. Mo is anomalous for the same reason as Cr. You won't get a question like that in the midterms or final exam.

This is one of the questions from MasteringChemistry.

If ml(angular momentum #) is 2, what are the possible values for l (for all atoms in their ground states that are known to exist)?

Could you explain how to get to the answer of 2,3?

Sure. It's basically saying what values of l allow you to attain an ml value of 2. Well, since ml can take all the values -l...0...+l, you can only get to a value of ml = 2 for orbitals with l values of at least 2. So this is l = 2 or 3 (d and f orbitals). Technically, it would also be true for even higher l value orbitals, but chemists only worry about the s, p, d, and f, because these are the only ones typically encountered.

Hi,

I'm looking at a picture on page 6 of the chem101 notebook (the one with all of the colourful arrows) and it shows a bunch of pink arrows, a bunch of green arrows then a bunch of red arrows. Does that mean an electron in hydrogen jumping from n=5 to n=1 will emit the same colour light as an electron jumping from n=3 to n=1? Thanks!

Hi,

I am doing question 1.31 from the Chem 101 textbook.

Can you please explain how to do part c?

"If molybdenum is irradiated with the wavelength of 120 nm, what is the maximum possible kinetic energy of the emitted electrons".

Thanks!

Will we be expected to identify different types of electromagnetic radiation based on their corresponding wavelengths/frequencies on the midterm? If so, will we be given an electromagnetic spectrum or must be memorize it?

We're not big on getting you to memorize stuff that is easy to just look up. Nonetheless, I would expect you to know SOME of this; for example, that UV light is more energetic than blue light and IR less so than red light (after all, there are clues in the names). I'm not terribly fussed about whether you remember that microwaves are shorter than radiowaves, though.

For the radial probability function, it seems that the peaks are around the middle of the orbital. For example, the 2p orbital ranges from about 0-7 angstroms but the optimum is at about 2....

With radial probability we multiply by the area, so it makes sense that we need to find this "maximum" between density and area.

However, i was wondering about the density graph...

If we look at the 2s orbital, and we only look at the function between the 1st and 2nd node...does density increase as you get farther from the nucleus?

the figure on page 9 of your notebook draws the darkest around the edges of the orbital.

However, for the 1s orbital, the density seems to decrease as you get farther.......

So, does density always start the largest right after the node, or is a maximum somewhere in the middle?

Remember, we're talking about density here not radial probability

Check out the Orbitron. And note that for radial probability, you're multiplying by volume, not area (I know the analogy I used in class - London - was for area not volume, but I don't know a good volume analogy!).

One of the textbook questions is: calculate the uncertainty in the position of a 1.50-mg mosquito moving at a speed of 1.40m/s if the speed is known to within +/- 0.01m/s. How would you solve this because I keep getting the wrong number but the correct power and there is no explanation in the answer key?

For the midterm, will we have to be able to recognize the different orientations of the electron orbitals, or just know the general shape for each?

903: Hard to comment without knowing more detail. Have you converted mg to kg? Ignored 1.4 m/s and just used 0.01 m/s? The answer ought to be delta x = h/4*pi*1.5*10-6*0.01.

906: you need to know the shapes, and that the labels tell you something about orientation. px orbitals point along the x axis. dxy lies in xy plane. dz2 points along z axis.

whats the difference between angular nodes and planar nodes? or there is two kinds of nodes right/

They're basically the same.

angular = planar (these differentiate between different l values)

radial = spherical (differentiate between different n value orbitals)

do we have to memorise the electromagnetic spectrrum and the individual wavelength and frequencies for the midterm

It wouldn't do any harm if you really like to memorize stuff, but given c = lambda.nu, why would you memorize both?

How do we calculate the number of radial nodes?

(The total # of nodes = n-1 and angular nodes = l, correct?)

Should we memorize the Rydberg equation and Rydberg constant for the final? Because in the formula sheet at the back of the lecture notebook, they are not present.

One of the mastering chemistry questions is "when light of wavelength 630nm is directed onto the photocell, electrons are emitted at the rate of 2.6×10−12C/s . Assume that each photon that impinges on the photocell emits one electron. How many photons per second are striking the photocell? How much energy per second is the photocell absorbing?" I am totally stuck.

Post a Comment