# Question 4a20d

Apr 16, 2015

Start by looking at the neutral argon atom, this will give you an idea about how the electron configuration of the $A {r}^{+}$ ion will look like.

Argon is located in period 3, group 18 of the periodic table, and has an atomic number equal to 18. This means that a neutral argon atom will have 18 electrons surrounding its nucleus.

Since you're dealing with the $A {r}^{+}$ ion, which has one less electron than neutral argon, the number of electrons that surround its nucleus will be 17.

${\text{Ar}}^{+} : 1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{5}$

Using the noble gas shorthand notation, this electron configuration will be

"Ar"^(+): ["Ne"] 3s^(2) 3p^(5)#