Covalent Bonding

  General Chemistry Index

Where are we going with this? This page will give the ability to use laboratory observations and data to compare and contrast ionic, covalent, network, metallic, polar, and non-polar substances with respect to constituent particles, strength of bonds, melting and boiling points, and conductivity; provide examples of each type.

Covalent Bonding
When atoms bond… 

Covalent bonding occurs when two atoms share one or more pairs of valence electrons. This usually occurs between two nonmetals. Sharing electrons can help each atom achieve a more stable valence-shell electron arrangement, often following the octet rule. 

You can think of it as commingling valence electrons…

So, many nonmetals already have several electrons in their valence shell but do not yet have a full valence shell. For these atoms, losing enough electrons to reach a stable electron arrangement would require a large amount of energy. Instead, when two nonmetals bond, they can become more stable by sharing valence electrons.

Compounds formed between nonmetals commonly contain covalent bonds. In covalent bonding, two atoms share one or more pairs of valence electrons.

This is covalent bonding…

When the electronegativity difference between two atoms is relatively small, neither atom attracts the bonding electrons strongly enough to completely take them from the other. Instead, the atoms share electrons, forming covalent bonds.

The shared electrons are attracted to the nuclei of both bonded atoms. This attraction holds the atoms together and creates the covalent bond.

Single, Double, and Triple Bonds

Sometimes one pair just isn’t enough…

Covalent bonds form when atoms share pairs of valence electrons.

The number of electron pairs being shared determines whether the bond is single, double, or triple.

Single bond: two atoms share one pair of electrons.

Example: H–H

Double bond: two atoms share two pairs of electrons.

Example: O=O

Triple bond: two atoms share three pairs of electrons.

Example: N≡N

In general, when comparing bonds between the same types of atoms, sharing more electron pairs results in a bond that is stronger and shorter.

So:

For bonds between the same types of atoms:

Single bond → generally longest and weakest

Double bond → generally shorter and stronger

Triple bond → generally shortest and strongest

Basically: between the same types of atoms, more shared electron pairs generally mean a stronger, shorter bond.

Single, double, and triple bonds can all help atoms achieve more stable valence-shell electron arrangements.

NOTE: Electrons are not always shared equally… and that leads us to polar covalent bonding.