### Electron Configuration

Posted:

**Sun May 06, 2018 8:01 pm**Why does the d-orbital start at 3 while the s and p start off at 1,2,.. and so on?

Created by Dr. Laurence Lavelle

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

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=31&t=31443

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Posted: **Sun May 06, 2018 8:01 pm**

Why does the d-orbital start at 3 while the s and p start off at 1,2,.. and so on?

Posted: **Sun May 06, 2018 8:26 pm**

The 4s orbitals fill first and have a lower energy than 3d, so the 4s needs to be filled first.

Posted: **Sun May 06, 2018 8:26 pm**

These numbers are determined by the l quantum number. The l number is the amount of orbitals an element can carry.

Posted: **Sun May 06, 2018 8:46 pm**

the first shell (n=0) only has one subshell, so it only has s orbitals. after that the second shell (n=1) has two subshells, and therefore has s and p orbitals. the third shell (n=2) has 3 subshells and therefore has s,p, AND d.

Posted: **Tue May 08, 2018 10:33 am**

KateCaldwell 1A wrote:These numbers are determined by the l quantum number. The l number is the amount of orbitals an element can carry.

how do you figure out the l quantum number

Posted: **Tue May 08, 2018 2:06 pm**

There isn't a formula to find l number; it is just standard numbers we need to know. s=0, p=1, d=2, f=3. The only other way to solve for it is through n-1= l max.

Posted: **Sun May 13, 2018 12:27 pm**

d is only present in the 3rd energy level and higher because in each energy level (1-4) an orbital (s p d f) is added. The first energy level only has an s orbital, the second has s and p, and the third has s, p, and d.