Question

Here below please describe the atomic structures showing one carbon atom and four hydrogen atoms sharing electrons to produce a molecule CH₄ (methane). How does the carbon atom share one of its electrons with each hydrogen atom to fill the valences of the hydrogen atoms and how does the carbon atom fill its valence shell (shell #2 for carbon) by sharing 4 electrons with the four hydrogen atoms?

Answer 1

In order for carbon to be stable, it needs eight valence electrons. It has only four, so it needs four more valence electrons.

In order for hydrogen to be stable, it needs two valence electrons. It has only one, so it needs one more to be stable.

So, one carbon atom would need to share with four hydrogen atoms to get enough valence electrons to fill its set. If one carbon atom shares electrons with four hydrogen atoms, the carbon atom will fill its set of valence electrons and become stable.

It is the configuration of atoms (not electrons) that defines the shape of a molecule. In case of methane, four regions of electron density associated with the valence shell. Thus, the tetrahedral geometry is expected.