What is the molecular geometry of a nitrogen molecule, #"N"_2# ?

1 Answer
Jan 7, 2016

Answer:

Linear.

Explanation:

In order to be able to determine the molecular geometry of a given compound, you need to first draw its Lewis structure.

Start by calculating how many valence electrons you'd get for a molecule of nitrogen gas, #"N"_2#.

Nitrogen is located in period 2, group 15 of the periodic table, which tells you that it has #5# valence electrons. This means that the nitrogen molecule will have a total of #10# valence electrons, #5# from each of the two nitrogen atoms.

Another important thing to realize about the fact that nitrogen has #5# valence electrons is that it needs #3# more to complete its octet.

This tells you that in order for both nitrogen atoms to have a complete octet, each must share three electrons with the other.

Therefore, you must draw a triple bond between the two nitrogen atoms. This will account for #3 xx 2 = 6# of the molecule's #10# valence electrons.

The remaining #4# valence electrons will be distributed as lone pairs, one of each nitrogen atom.

http://nonsibihighschool.org/acchonch9.php

Now, molecular geometry is all about regions of electron density, that is, about how many regions of electron density surround a given atom.

Remember, a region of electron density is

  • a single, double, or triple bond - they all count as one region of electron density
  • a lone pair of electrons

So, pick one of the two nitrogen atoms and count how many regions of electron density surround it - this is called the steric number.

In this case, one triple bond and one lone pair will amount to two regions of electron density. This means that the atoms have a steric number equal to #2#, which implies that they are #"sp"# hybridized.

According to VSEPR Theory, this molecule falls into the #"AX"# category, i.e. one bond, #"A"#, and one lone pair, #"X"#.

Therefore, the molecular geometry for this molecule will be linear, with a bond angle of about #180^@#.

https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/