# How do you determine the electron configuration for the f block?

Nov 24, 2017

See below.

#### Explanation:

It's easier to understand how the f orbital fills using the long periodic table without the lanthanides and actinides removed:

The f orbital will be 2 energy levels behind the row it's in, like how the d orbital in row 4 is 1 energy level behind (like in $4 {s}^{2} 3 {d}^{10} 4 {p}^{3}$ with the d orbital, but $6 {s}^{2} 4 {f}^{14} 5 {d}^{10} 6 {p}^{3}$ with the f orbital).

The way you determine the number of electrons in an f orbital is the same way as the s, d, and p orbitals: count from left to right in the f block.

For example, La has 1 electron in the f orbital, Ce has 2, Pr has 3, Yb has 14, etc.

Hope this helped!