Covalent bonding

Molecules are groups of atoms bonded together

Molecules form when two or more atoms bond together. Molecules are held together by covalent bonds. In this atoms share electrons so that they can both get a full outer shell.

A covalent bond is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Some covalent compounds are special cases

A few compounds have less than 8 electrons in their outer shell

and a few can use d orbitals to expand the octet so that they can have more than 8 electrons

Some atoms share more than one pair of electrons

Atoms can form double or even triple bonds. These share more than one pair of electrons.

Dative covalent bonding is where both electrons come from one atom

For example an ammonium ion (NH₄⁺) is formed by dative covalent bonding. When the nitrogen in ammonia donates a pair of electrons to a proton (H⁺)