# Question 8ce42

Jun 27, 2015

Actually, arsenic has 5 electrons in its outermost shell.

#### Explanation:

Arsenic, $A s$, is located in period 4, group 15 of the periodic table and has an atomic number equal to 33.

This means that a neutral arsenic atom has 33 electrons surrounding its nucleus. The electron configuration for arsenic looks like this

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

or, using the noble gas shorthand notation

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

As you can see, the outermost shell is the fourth shell, $n = 4$. This shell contains a total of 5 electrons, 2 in the 4s-orbital and 3 in the 4p-orbitals.

Since arsenic is not a transition metal, its valence electrons will be those electrons located in its outermost shell $\to$ 5 valence electrons.