Key Concepts: Covalent Bonding

Covalent bonds are a type of chemical bond that involve the sharing of electron pairs between atoms.
They are usually formed between two non-metals.
The shared pair of electrons is attracted to the nucleus of both atoms, holding them together and creating the bond.
Each shared pair of electrons forms a single covalent bond. Two pairs form a double bond, while three pairs form a triple bond.
Simple molecular structures are created by covalent bonds and can consist of just a few atoms. For example: H2O (water).
Larger covalent structures, such as those in diamond or silicon dioxide, are known as giant covalent structures or macromolecules. These substances generally have high melting and boiling points due to the many strong covalent bonds that need to be broken.
In covalently bonded molecules, different atoms may pull shared electrons with different strengths. This is known as electronegativity. When this difference is great, the bond is polar, with a partial negative charge on one atom and a partial positive charge on the other.
Covalent substances typically do not conduct electricity because they do not have free electrons or ions.
Their low melting and boiling points mean that covalent substances are usually liquids or gases at room temperature.
Covalent substances are poor conductors of heat as their particles are not closely packed together.
Full outer shells are formed during covalent bonding, which gives the atoms involved stable electron configurations.
The bonding in organic chemistry, the chemistry of carbon-based molecules, is mostly covalent.