Question

What is the number of dots in the electron dot symbol of nitrogen?

Answer 1

In dinitrogen gas, `N_2`, there are 5 valence electrons associated with each nitrogen atom.

Explanation:

`N`, `Z=7`, and thus 7 electrons associated with the neutral atom.

Two of these electrons are inner core, and do not participate in bonding. The remaining 5 electrons are the valence electrons, and 6 of these bind between the nitrogen nuclei together in forming chemical bonds.

Given that a single bond is composed of 2 electrons, the `:N-=N:` representation clearly shows the disposition of the 10 remaining electrons.

If we look at nitrogen compounds, the simplest one is ammonia, `:NH_3`, which is (i) hard to make; and (ii) absolutely vital to agriculture. Nitrogen here is considered to be neutral because it has 2 electrons from its lone pair, and a half share of the 6 electrons that make up the `3xxN-H` bonds. `5+2" inner shell electrons"` balance the charge of the 7 protons in the nitrogen nucleus.

But nitrogen is a base, and has a formal lone pair, which is conceived to form a donative bond to `H^+` in an acid base reaction:

`NH_3(aq) + H_2O rightleftharpoons NH_4^+ + HO^-`

The nitrogen centre is now quaternized, and is depicted with a formal positive charge (6 electrons rather than the 7 required for neutrality).