### Electron Configuration Clarification

Posted:

**Fri Oct 19, 2018 4:26 pm**In class today (Lecture 3), Lavelle said that an electron could not have the configuration (1,1,0). I am confused, why not?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=23&t=34257

Page **1** of **1**

Posted: **Fri Oct 19, 2018 4:26 pm**

In class today (Lecture 3), Lavelle said that an electron could not have the configuration (1,1,0). I am confused, why not?

Posted: **Fri Oct 19, 2018 4:29 pm**

I believe this is because "l" has to be n-1. n=the first quantum number, and l=the second quantum number.

Posted: **Fri Oct 19, 2018 5:06 pm**

Madison is correct,

The first quantum number (n) is a positive integer (0,1,2,3 .....)

The second quantum number (l) is any positive integer that is less than n, thus (0,1,2,3..... n-1)

The reason why (1,1,0) doesn't work is because n=1, which means the only value possible for l can be 0. If n=2, then the l-value could be 0 or 1.

The first quantum number (n) is a positive integer (0,1,2,3 .....)

The second quantum number (l) is any positive integer that is less than n, thus (0,1,2,3..... n-1)

The reason why (1,1,0) doesn't work is because n=1, which means the only value possible for l can be 0. If n=2, then the l-value could be 0 or 1.