Key concepts in chemistry Study Guide

Ionic compounds form a specific arrangement known as a giant ionic lattice structure. This structure is characterised by a regular, repeating pattern of oppositely charged ions, extending in three dimensions. The strong electrostatic forces of attraction between these positive and negative ions are called ionic bonds. These forces act in all directions and hold the entire lattice together, requiring a significant amount of energy to overcome. This strong bonding and orderly arrangement result in properties such as high melting and boiling points, and often solubility in polar solvents.

A covalent bond forms when two atoms share one or more pairs of electrons. This sharing occurs between non-metal atoms, allowing each atom to achieve a stable outer electron shell configuration, typically resembling that of a noble gas (e.g., a full outer shell of 8 electrons, or 2 for hydrogen). The electrostatic attraction between the positively charged nuclei of the atoms and the negatively charged shared electron pair holds the atoms together. Unlike ionic bonding where electrons are transferred, in covalent bonding, the electrons are mutually attracted to both nuclei involved in the bond, resulting in a strong force that forms a stable molecule.