# Covalent bond

A bond made when two atoms share a pair of electrons. It forms between non-metal atoms.

Chemistry (school) · Part 03: Bonding and structure · Card 3 of 9 · Last updated 2026-10-19

## Analogy

Two people hold the same rope. Both are held together by what they share.

## Example

**Bonds in molecules**

H2: 1 shared pair
O2: 2 shared pairs (double bond)
H2O: 2 bonds
CH4: 4 bonds

## In practice

In water, each hydrogen atom shares a pair of electrons with the oxygen atom.

## Practice

### Flashcards

- **What type of bond forms between two non-metals?** A covalent bond.

### Interview questions

**Explain why diamond is very hard but graphite is soft, even though both are made only of carbon.**

- Diamond: each carbon bonded to four others
- Strong covalent bonds in all directions
- Graphite: each carbon bonded to three others in layers
- Weak forces between layers let them slide

## Questions people ask

### What is a double bond?

A double bond is two shared pairs of electrons between the same two atoms. In oxygen gas, O2, each atom shares two electrons with the other. A double bond is stronger and shorter than a single bond. Carbon dioxide has two C=O double bonds.

### Why do covalent bonds not conduct electricity?

In a covalent bond the electrons are fixed between two atoms. There are no free electrons and no ions to carry charge. So most substances with covalent bonding, such as water and sugar, do not conduct electricity. Graphite is an exception, with a free electron per atom.

## Related concepts

- [Giant covalent structure](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-3/chemistry-school-part-3-concept-7)
- [Allotrope](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-3/chemistry-school-part-3-concept-8)
- [Simple molecule](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-3/chemistry-school-part-3-concept-6)

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