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Ionic, covalent and metallic bonding
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Atoms join together in three main ways. The type of bond explains melting points, conductivity and more.
Ionic bonding
A metal and a non-metal. The metal atom loses electrons and the non-metal gains them, forming oppositely charged ions.
Group 1 forms 1+ ions, group 2 forms 2+, group 6 forms 2−, group 7 forms 1−.
Ionic compounds form giant lattices with high melting points. They conduct electricity when molten or dissolved.
Group 1 forms 1+ ions, group 2 forms 2+, group 6 forms 2−, group 7 forms 1−.
Ionic compounds form giant lattices with high melting points. They conduct electricity when molten or dissolved.
Covalent bonding
Two non-metals share pairs of electrons.
Simple molecules such as H2O have low melting points.
Giant covalent structures such as diamond and graphite have very high melting points.
Simple molecules such as H2O have low melting points.
Giant covalent structures such as diamond and graphite have very high melting points.
Metallic bonding and formulae
Metals have positive ions in a sea of delocalised electrons, so they conduct electricity.
To write an ionic formula, balance the charges. Mg2+ and Cl− need two chloride ions: MgCl2.
To write an ionic formula, balance the charges. Mg2+ and Cl− need two chloride ions: MgCl2.
Write the formula of sodium oxide.
- Sodium is in group 1, so it forms Na+.
- Oxygen is in group 6, so it forms O2−.
- Two Na+ balance one O2−.
- Formula: Na2O
Answer: Na2O
Ionic: metal plus non-metal, electrons transferred. Covalent: non-metals share pairs. Metallic: positive ions in delocalised electrons. Balance charges to write formulae.
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