electron structure question

[ahamdi2]

what is the electron structure of an excited Cu (I) ion?

so to began with the structure of Cu (not the ion) is : [Ar] 4s2 3d9

if we excite one of the electrons and it jumps to the next orbital we get
[Ar] 4s1 3d10


but the answer key is saying [Ar] 4s1 3d10 is the non excited structure and [Ar] 3d9 4p1 is the excited structure

Is it right to start filling the 3d orbital before fully filling the 4s orbital? and if someone can direct me to the rules on how to fill orbitals

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[deleted329605]

So yea if you ionize something, it has to have one less electron that its elemental state. Then you just move one of the e- up to a higher energy level. It terms of comparing the relative energy levels, look at the periodic table. If you read it like a book, left to right it'll give you the order of lowest to highest energy orbitals. So in the fourth period, it goes
4s->3d->4p meaning electrons in the 4s are at a lower energy than in 3d. however you have to remember when removing electrons you always take it from the highest numbered orbital. That's to say if you have electrons in the 4s and 3d and you ionize that species, you'll take it from the 4s because 4>3.

Hope that helps

 

[Labminion]

Actually, the correct electron configuration for copper (I) is [Ar] 4s1 3d10, not [Ar] 4s2 3d9. Copper is one of the "exceptions" to the filling rules, in that one of its 4s electrons will be promoted to the slightly higher energy 3d level because it is more stable with a completely-filled 3d subshell. The first electron that will be ionized will come from the 4s subshell; therefore, one of the ten 3d electrons will be excited to the 4p level in the Copper (I) ion to yield: [Ar] 3d9 4p1.

Hope that helps.

 

[MD Odyssey]

however you have to remember when removing electrons you always take it from the highest numbered orbital. That's to say if you have electrons in the 4s and 3d and you ionize that species, you'll take it from the 4s because 4>3.

Keep in mind that you aren't necessarily taking it from the highest energy orbital. In the first-row transition elements, the highest energy electrons are the ones in the 3d orbitals. However, the 4s electrons are further from the nucleus and are easier to remove. Also, you might want to take a little bit of time to study chromium and copper, since they are the exceptions.

Anyone have any idea if this sort of detail is normal for the MCAT? The Berkeley Review seems to be really excited about this kind of minutia, but I have no idea whether it's beyond what the MCAT usually tests.

 

[whiteshadodw]

what is the electron structure of an excited Cu (I) ion?

so to began with the structure of Cu (not the ion) is : [Ar] 4s2 3d9

if we excite one of the electrons and it jumps to the next orbital we get
[Ar] 4s1 3d10


but the answer key is saying [Ar] 4s1 3d10 is the non excited structure and [Ar] 3d9 4p1 is the excited structure

Is it right to start filling the 3d orbital before fully filling the 4s orbital? and if someone can direct me to the rules on how to fill orbitals

Cu [Ar]4s1 3d10 <=Prefers a filled d subshell, leaving s with 1

from:
http://www.science.uwaterloo.ca/~cchieh/cact/c120/eleconfg.html

basically, Cr and Cu are exceptions to the rule because a half-filled or completely filled d-orbital has enormous amounts of stability. therefore, an electron is more likely to be lost from the s orbital, which is also further away from the nucleus, despite being lower in energy. as such, the single electron in the 4s orbital probably gets bumped up to the next available orbital, probably being 4p.

this question is a little too tricky to be quite honest with you. the MCAT tests basic concepts. if there is a question like this on the MCAT, there will be at most 1-2 of these types of questions.