Covalent Bonding

Covalent bonds

• A covalent bond is a shared pair of electrons between two atoms. The bond is strong
• Covalent bonding happens in most non-metal elements and in compounds of non-metals
• Covalently bonded substances come in three sizes:
  • Small molecules, such as $\text{H}_2$, $\text{Cl}_2$, $\text{O}_2$, $\text{N}_2$, HCl, $\text{H}_2\text{O}$, $\text{NH}_3$, $\text{CH}_4$
  • Polymers: very large molecules with thousands of atoms in a chain
  • Giant covalent structures, such as diamond and silicon dioxide
• You can usually recognise a small molecule from its formula: only non-metal atoms, and only a few of them