1.28 Explain how a covalent bond is formed when a pair of electrons is shared between two atoms
- Particles are atoms which share pairs of electrons
- Covalent bonding occurs in most non-metallic elements and in compounds of non-metals
- When atoms share pairs of electrons, they form covalent bonds. These bonds between atoms are strong.
1.29 Recall that covalent bonding results in the formation of molecules
- Covalently bonded substances may consist of small molecules e.g. HCl, H2, O2, Cl2, NH3, CH4.
- Some have very large molecules, such as polymers.
- Some have giant covalent structures (macromolecules) e.g diamond, silicon dioxide.
- Diagrams to show these substances could be dot and cross, shown as repeat units for polymers using a single line to represent a single bond, ball and stick and two- and three-dimensional diagrams.
1.30 Recall the typical size (order of magnitude) of atoms and small molecules
- Simple molecular substances consist of molecules in which the atoms are joined by strong covalent bonds
- Therefore, atoms are smaller than small molecules