Definition
To be 'ionised' (British spelling) means to have gained or lost electrons, resulting in a net electric charge. Atoms are usually neutral, but when they gain or lose electrons, they become ions. Think of salt dissolving in water; the sodium and chloride atoms become 'ionised'. ⚡️ The process of ionisation can happen through chemical reactions or exposure to radiation. Imagine rubbing a balloon on your hair; the hair becomes 'ionised' and sticks to the balloon. Ionisation is fundamental to chemistry and physics.