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Science

Covalent bonding

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A covalent bond is formed between non metal atoms, which combine together by sharing electrons. Covalent compounds have no free electrons and no ions so they don't conduct electricity.

The Periodic Table is an arrangement of the elements in order of atomic number. Elements in the same vertical column are in the same group or family and have similar chemical properties.

Covalent bonding

Non metals combine together by sharing electrons. The shared pair of electrons holds the two atoms together. It's called a covalent bond. The group of atoms bonded together in this way is called a molecule.

The types and numbers of atoms in a molecule are shown in its formula.

Examples of covalent molecules

NameStructureModel
Hydrogen (H2)H - Htwo atoms joined with a straight horizontal line
Water (H2O)H - O - Hthree atoms joined
Ammonia (NH3)H - N - H (with a line down from the N to an H) four atoms joined
Methane (CH4)H - C - H in a row, line from above the C to an H, line from below the C to an H five atoms joined

Covalent compounds are usually gases or liquids with low melting points or boiling points and they don't conduct electricity.

Example:

Carbon dioxide is a gas with a boiling point of -44°C. It doesn't conduct electricity.

Water is a liquid with a melting point of 0°C. It doesn't conduct electricity.

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