Thanks for the feedback. I don't teach Chem102, though I'm the only 101 instructor not to - Drs Briggs, Chak & Codding will be teaching 102 next semester.
I'm assuming that London forces not only depend on molecular weight but also on Zeff right? I mean...if we have higher Zeff the electrons won't be so free to move around...thanks!
Certainly the polarizability of the atom/molecule is important (and this has to do with how easily the electrons can move in response to an instantaneous dipole), but Zeff is less important than number of electrons: O2 has a higher boiling point than N2, because it has more electrons and this makes up for the fact that they're held more tightly. So I would say molecular weight and molecular shape are the most important factors (in that order).
A) high mobility B) low melting point and softness C) High melting point and poor electrical conductivity D) Charged particles throughout E) Good electrical conductivity
The answer (they say) is B...is this correct? The textbook says covalent-networks exhibit high melting points and hardness.
10 comments:
Just a question... do you ever teach Chemistry 102? If so might you teach it next semester?
Thanks!
PS:Love your class
Thanks for the feedback. I don't teach Chem102, though I'm the only 101 instructor not to - Drs Briggs, Chak & Codding will be teaching 102 next semester.
I am not in the class, but it would be useful if u can give me the multiple choice answers for the other sample midterm you posted.
Thanks
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I'm assuming that London forces not only depend on molecular weight but also on Zeff right? I mean...if we have higher Zeff the electrons won't be so free to move around...thanks!
Certainly the polarizability of the atom/molecule is important (and this has to do with how easily the electrons can move in response to an instantaneous dipole), but Zeff is less important than number of electrons: O2 has a higher boiling point than N2, because it has more electrons and this makes up for the fact that they're held more tightly.
So I would say molecular weight and molecular shape are the most important factors (in that order).
Hi I was wondering whether the midterm will cover superconductors
No, it won't.
A practice exam I bought has this question:
A covalent-network solid is characterized by:
A) high mobility
B) low melting point and softness
C) High melting point and poor electrical conductivity
D) Charged particles throughout
E) Good electrical conductivity
The answer (they say) is B...is this correct? The textbook says covalent-networks exhibit high melting points and hardness.
No, that answer is wrong - it should be C. The marked finals are produced in good faith by the student society but unfortunately do contain errors.
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