Destroyer'13 Q's GC

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hope_to_match

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Q45: Barium is an alkaline earth metal with the atomic number 56. Which set of quantum numbers may be written for a valence electron for barium

I narrowed it down to answer choices B (n=6, l=0, ml=0, ms=-1/2) and D (n=6, l=2, ml=2, ms=+1/2). In the solutions, the correct choice is B. I am not sure why D can't be the answer, since ml can be from -l...+l?? this satisfies both B and D...


Q50: Which statement is false? a) Kr has a lower average speed than Ne at the same temperature b) the molecules of a gas undergo many collisions with each other and with the walls of the container c) deviations from the ideal gas law are greater at low temperatures and high pressures d) all molecules of an ideal gas have the same kinetic energy at constant temperature e) all are true

The correct answer is D. I thought all statements are true? I looked over Chad's notes and I thought that the average KE of Oxygen, for example, would equal the average KE of hydrogen...can someone clarify this for me? Why the destroyer says that the molecules wouldn't have the same kinetic energy at constant temperature? I thought the speed/velocity would differ depending on the weight of an atom, but not the kinetic energy.

Thanks.

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for #45, Ba's electron configuration ends with 6s2. It's in the S subshell. the azimuthal for S is always 0(zero). So n=6 and l=0. Ml has to equal 0 as well.
 
For 50 the question tricks you because it is talking about the molecules of the gas which moves at different speeds and kinetic energies. The average kinetic energies of the gas sample as the same but not the molecules of the gas.

hope that helps
 
for #45, Ba's electron configuration ends with 6s2. It's in the S subshell. the azimuthal for S is always 0(zero). So n=6 and l=0. Ml has to equal 0 as well.

thank you i get it now..that slipped my mind for a sec that spdf is 0,1,2,3 respectively...for azimuthal..

For 50 the question tricks you because it is talking about the molecules of the gas which moves at different speeds and kinetic energies. The average kinetic energies of the gas sample as the same but not the molecules of the gas.

hope that helps

not really..do you mind elaborating on this :)
 
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thank you i get it now..that slipped my mind for a sec that spdf is 0,1,2,3 respectively...for azimuthal..



not really..do you mind elaborating on this :)

D is the correct answer. It says that they have the same kinetic energy. They don't. They have the same AVERAGE kinetic energy. I think that's what they're trying to get you to realize. KE is average. I didn't look into the answer to that question much other than that I realized the whole part about KE being average because not every single particle of gas is moving at the same speed. They're colliding with each other and when this happens, the speeds can cancel each other out, or the speed of one can increase while the other decreases (like billiard balls).
 
D is the correct answer. It says that they have the same kinetic energy. They don't. They have the same AVERAGE kinetic energy. I think that's what they're trying to get you to realize. KE is average. I didn't look into the answer to that question much other than that I realized the whole part about KE being average because not every single particle of gas is moving at the same speed. They're colliding with each other and when this happens, the speeds can cancel each other out, or the speed of one can increase while the other decreases (like billiard balls).

yes...that's right..AVERAGE is what I missed...

thanks. your explanation helped a lot :)
 
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