genchem question

[Shjfr]

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Okay so I was doing an MCAT from Kaplan (friend of mine has it) and I'm a little confused about this gen chem question: basically an electron is excited to another orbital, and it is asking which transition is possible.

1. 4f to 6s
2. 3p to 4s
3. 5p to 5s
4. 4s to 3s

I know that you want to go from lower energy to higher energy, so you would use the (n+l) rule. What I am confused about is that the answer says to use l=0 for s, l=1 for p, l=2 for d, and l=4 for f... so the answer is choice 2 (they both add to 5, but 3 is less than 4). I thought that the answer could also be choice 1 (I thought l=3 for f). Can anyone explain whether or not l=3 or 4 for f? Maybe both depending on the circumstance?

 

[Contach]

Okay so I was doing an MCAT from Kaplan (friend of mine has it) and I'm a little confused about this gen chem question: basically an electron is excited to another orbital, and it is asking which transition is possible.

1. 4f to 6s
2. 3p to 4s
3. 5p to 5s
4. 4s to 3s

I know that you want to go from lower energy to higher energy, so you would use the (n+l) rule. What I am confused about is that the answer says to use l=0 for s, l=1 for p, l=2 for d, and l=4 for f... so the answer is choice 2 (they both add to 5, but 3 is less than 4). I thought that the answer could also be choice 1 (I thought l=3 for f). Can anyone explain whether or not l=3 or 4 for f? Maybe both depending on the circumstance?

f=3, it must if the order of subshells is s, p, d, f, g, ...
So 4f = (4+3) = 7, and 6s = (6+0) = 6.. therefore 4f is a higher energy level than 6s and an electron excited CANNOT go from 4f to 6s... I don't see what problems you are having. Even if you though f = 4, you would still come to the same answer...

 

[nixon13]

The answer is 3p to 4s. s=0, p=1, d=2, f=3. So when an electron is excited, it moves to a higher energy level. The energy in 3p is (3+1)=4 and the energy in 4s is (4+0)=4. They both equal 4 but the principal quantum number is higher in 4s than 3p. So you know from 3p to 4s is jumping to a higher energy level. If you try all the other ones in the same manner, you will go from a higher energy level to a lower one.

 

[Simiam]

Worst case scenario just look at your answer options...

4f to 6s = (4+4) --> (6+0) = 8 --> 6
3p to 4s = (3+1) --> (4+0) = 4 --> 4
5p to 5s = (5+1) --> (5+0) = 6 --> 5
4s to 3s = (4+0) --> (3+0) = 4 --> 3

You know that electrons that are excited move to a higher energy level. By looking at the results of your basic calculations you can determine that A, C, and D cannot be correct because they all move to a lower energy level. This leads you to look at option B which moves to a higher principal quantum number.

 

[jdent]

I understand where you all are confused, but this is a question based on fundamentals of quantum stuff. If an electron is excited it will go up to a higher energy group. Normally its s,p,d,f.....
1. 4f to 6s
2. 3p to 4s
3. 5p to 5s
4. 4s to 3s
The answer is choice 2 because after 3p is 4s. Choice 4 - 3s is lower then 4s. 4f doesnt tn go to 6s and 5s is before 5p.
Very easy question.

 

[Shjfr]

I was accidently using s=1 and f=3 for part A, making it 7=7.

Oops. 😡

Sorry, easy question.

 

[yakuza]

Worst case scenario just look at your answer options...

4f to 6s = (4+4) --> (6+0) = 8 --> 6
3p to 4s = (3+1) --> (4+0) = 4 --> 4
5p to 5s = (5+1) --> (5+0) = 6 --> 5
4s to 3s = (4+0) --> (3+0) = 4 --> 3

You know that electrons that are excited move to a higher energy level. By looking at the results of your basic calculations you can determine that A, C, and D cannot be correct because they all move to a lower energy level. This leads you to look at option B which moves to a higher principal quantum number.

What did you just do..?
This question is a basic common sense problem that only involves looking at the periodic table, no math.

A. 4f cant go to 6s at all..
B. 3p10 bumps to 4s when you add an electron---Correct
C. 5p cant go backwards to 5s
D. 4s cant go backwards to 3s