Use dot-cross diagrams to illustrate the bonding in covalent compounds.
Outline the properties of simple molecules
Covalent bonds occur between nonmetals, which could be of the same element, or different elements.
The atoms involved in a covalent bond share one or more electron pair(s).
Covalent bonding is the electrostatic force of attraction between the nuclei of the non-metallic atoms and their shared pairs of electrons.
Atoms participate in sharing electron pairs, to gain a stable electronic configuration.
Formation of Covalent Bonds
We draw dot and cross diagrams with overlapping valence electron shells, to illustrate how covalent bonds are formed. The diagrams below illustrate the formation of a single and a double covalent bond.
Covalent Compounds – Properties
Covalent bonding forms simple covalent compounds, or giant covalent compounds.
Simple covalent compounds are called molecules.
Are usually gasses (such as oxygen and ammonia molecules) or liquids (such as water and cooking oil) under normal conditions of temperature and pressure.
have low melting and boiling points, because although they have strong intramolecular forces of attraction (covalent bonds), they have weak intermolecular forces that hold the molecules together. So, only a small amount of energy is required to break the molecules apart during heating.
lack the ability to conduct electricity in any state as they do not have any free delocalized ions or electrons, to carry an electric charge.
Can be polar or nonpolar.
Polar bond – electrons unevenly shared between atoms which have different electronegativity strength. For e.g., water.
Non-polar – electrons shared evenly in the bond; i.e., no difference in electronegativity. For e.g., chlorine molecule.