## Homework 2.43

camrynpatterson3C
Posts: 44
Joined: Fri Sep 29, 2017 7:07 am

### Homework 2.43

Why is the electron configuration for Silver, [Kr]4d^10 5s^1, instead of [Kr]4d^9 5s^2?
Also, why is the electron configuration for Tungsten, [Xe]4f^14 5d^4 6s^2, instead of [Xe]4f^14 5d^3 6s^2? And for this, do we always have to write the f orbital in the configuration if the element is in row 6 or 7?

Taylor 1F
Posts: 17
Joined: Thu Jul 27, 2017 3:00 am

### Re: Homework 2.43

For your first question, Silver is 4d^10 5s^1 because this allows the atomic sub shells to be more stable since the d block is filled and the valence of electron (5s^1) is easily attainable

AlyssaPeckham1A
Posts: 49
Joined: Fri Sep 29, 2017 7:04 am

### Re: Homework 2.43

For your second question, the electron configuration for tungsten is [Xe]4f^14 5d^4 6s^2 instead of [Xe]4f^14 5d^3 6s^2 because tungsten is located in the fourth space over from the start of the d block in period 6. Therefore it's noted as 5d^4 instead of 5d^3. Because the answers for the homework include the f orbital in the electron configuration, I have been writing in the f orbital.

Abigail Urbina 1K
Posts: 102
Joined: Thu Jul 27, 2017 3:01 am

### Re: Homework 2.43

To answer the first question, the reason the electron configuration for silver is [Kr]4d^10 5s^1 instead of [Kr]4d^9 5s^2 is because when you are one electron away from a half-full or fully d shell, it is actually lower in energy to fully fill the d shell and to leave the s orbital singly occupied with only 1 electron. Keep in mind the fact that the d shell has a lower principle number (4) than the principle number of the s shell (5). Filling all of the d orbital before moving on to the higher s orbital makes Ag more stable.

Posts: 88
Joined: Fri Sep 29, 2017 7:03 am

### Re: Homework 2.43

Hi I just had a follow up question about the second part. Why isn't the electron configuration for Tungsten [Xe] 4f^145 d^5 6s^1? I remember Dr. Lavelle talking about exceptions during a lecture, and one of them included chromium, which would want to have a half full d^5 orbital. Why doesn't Tungsten follow this trend if it is in the same group as chromium?

Thanks