Covalent Bonding
Year 9 ⚛️ Particles & Structure Describe covalent bonding as electron sharing; draw dot-and-cross diagrams.
🔗 Covalent Bonds
A covalent bond is formed when two atoms share a pair of electrons. This occurs between non-metal atoms.
| Molecule | Bonds | Formula |
|---|---|---|
| Water | 2 O-H single bonds | H₂O |
| Carbon dioxide | 2 C=O double bonds | CO₂ |
| Methane | 4 C-H single bonds | CH₄ |
| Nitrogen | 1 N≡N triple bond | N₂ |
🏗️ Simple Molecular Structures
Simple covalent compounds exist as small molecules with weak intermolecular forces between them.
Properties
$$\text{Low melting/boiling points (weak intermolecular forces)}$$
$$\text{Do not conduct electricity (no free ions or electrons)}$$🔬 Giant Covalent Structures
Some substances form giant lattices where all atoms are covalently bonded — very high melting points.
Diamond: each C bonded to 4 others — hardest natural substance, no electrical conductivity.
Graphite: layered structure, delocalised electrons — conducts electricity, good lubricant.
Silicon dioxide (SiO₂): sand, glass — hard, very high melting point.
Graphite: layered structure, delocalised electrons — conducts electricity, good lubricant.
Silicon dioxide (SiO₂): sand, glass — hard, very high melting point.
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Interactive Demonstration — Covalent Bonding
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