# What is the valence electronic configuration of f - Block elements?

Jul 15, 2017

The f-block is that pesky, enigmatic block of elements below the table you usually look at, but kicker—it's supposed to be between the s and d blocks!

So, for instance, looking at $U$

We have,
$U$:$\left[R n\right] 7 {s}^{2} 5 {f}^{4}$

In an anomalous case, which is quite nuanced (which you may not need to know), $U$ actually has a different electron configuration than expected:

$U$:$\left[R n\right] 6 {s}^{1} 7 {s}^{2} 5 {f}^{3}$