# What is the correct Lewis structure for arsenic?

Apr 30, 2016

Arsenic is isoelectronic with nitrogen (they are both Group V elements), so there are 5 valence electrons.

#### Explanation:

Look at the position of arsenic in the Periodic Table. It is under phosphorus, which is under nitrogen. These elements are thus isoelectronic, and their chemistry should be similar to a first approximation.

Consider ammonia versus phosphine versus arsine, i.e. $N {H}_{3}$ versus $P {H}_{3}$ versus $A s {H}_{3}$. All of these hydrides have a formal lone pair of electrons, and should thus be isostructural.