# How many nitrogen atoms are in each formula unit of lead(II) nitrite Pb(NO_2)_2?

Why $2$ nitrogen atoms.
We have the one formula unit of $\text{lead nitrite, } P b {\left(N {O}_{2}\right)}_{2}$. This is one lead atom, 2 nitrogen atoms, and 4 oxygen atoms. The bracketed part of the formula is expanded out on multiplication.
$\text{Lead azide}$, $P b {\left({N}_{3}\right)}_{2}$, is commonly used a detonator. How many nitrogen atoms are in 1 formula unit?