Covalent Bonding

This lesson covers covalent bonding — the sharing of electron pairs between non-metal atoms — as required by the Edexcel GCSE Chemistry specification (1CH0). You need to understand how covalent bonds form, draw dot-and-cross diagrams for a range of molecules, and recognise single, double and triple bonds.

---

What Is Covalent Bonding?

A covalent bond is a shared pair of electrons between two non-metal atoms. Covalent bonding occurs between non-metals only.

Each atom in the bond contributes one electron to the shared pair (in a single bond). The shared pair of electrons is attracted to the nuclei of both atoms, holding the atoms together.

Why do atoms form covalent bonds?

• Non-metal atoms need to gain electrons to achieve a full outer shell.
• When two non-metal atoms are close together, instead of one atom taking electrons from the other, they share electrons.
• By sharing, both atoms can achieve the electronic structure of a noble gas (full outer shell).

Exam Tip: A covalent bond is a "shared pair of electrons." This is the definition the examiner expects. Don't just say "sharing electrons" — specify that it's a pair.

---