# What is the noble gas notation for K 19?

May 8, 2014

K 19 refers to Potassium on the periodic table found in the Alkalai Metals first column on the left IA and in the fourth energy level (row).

This means that potassium must end with an electron configuration of $4 {s}^{1}$
The total electron configuration would be
$1 {s}^{2} 2 {s}^{2} 2 {P}^{6} 3 {s}^{2} 3 {p}^{6} 4 {s}^{1}$

The noble gas Argon has an electron configuration of
$1 {s}^{2} 2 {s}^{2} 2 {P}^{6} 3 {s}^{2} 3 {p}^{6} 4 {s}^{1}$

So we can replace this portion of potassiums electron configuration with the noble gas notation [Ar]

This makes the electron configuration for potassium
$\left[A r\right] 4 {s}^{1}$