# What's the electronic configuration for an atom that has 33 electrons?

Jan 6, 2015

The (neutral) atom that has 33 electrons is called Arsenic ($A s$), and its electron configuration can be written like this:

$\text{As} : 1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6} 4 {s}^{2} 3 {d}^{10} 4 {p}^{3}$

Another way to write the electron configuration for $A s$ is to use the noble gas shorthand notation. This is done by determining the noble that comes before $A s$ in the periodic table, which is Argon ($A r$).

The electron configuration for $A r$ is

$\text{Ar} : 1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6}$

Using this to replace the matching portion of $A s$' configuration will give

"As": ["Ar"]4s^(2)3d^(10)4p^(3)