# What is the electron configuration of Sr2+?

Oct 17, 2015

$1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 3 {d}^{10} 4 {s}^{2} 4 {p}^{6}$

#### Explanation:

Strontium is atomic number 38 so its electron configuration can be written:

$2.8 .18 .8 .2$

In orbital notation this is:

$1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 3 {d}^{10} 4 {s}^{2} 4 {p}^{6} 5 {s}^{2}$

The noble gas shorthand notation is:

$\left[K r\right] 5 {s}^{2}$

When strontium forms a 2+ ion the 2 outer $5 s$ electrons are lost so $S {r}^{2 +}$ can be written as:

$1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 3 {d}^{10} 4 {s}^{2} 4 {p}^{6}$

Or:

$\left[K r\right]$