How many pairs of electrons are shared between two adjacent carbon atoms in a saturated hydrocarbon?

1 Answer
May 1, 2016

How many pairs? Just the one.


Consider the ethane molecule, #H_3C-CH_3#. Each carbon atom has 6 electrons, 2 of which are inner core and are along for the ride. Thus, there are 4 electrons in the valence shell.

When carbon makes music with the hydrogen atom (1 electron), 2 electrons are conceived to form the #H-C# bond. So far we have #H_3C*#, a neutral carbon radical.

So the free electron on one carbon nucleus is conceived to couple to form a #C-C# bond:

#H_3C*+*CH_3 rarr H_3C-CH_3#

Of course, all of this is a formalism. But you can use this approach to assign formal charge.