Atomic theory describes atoms as made up of three different components. In the centre of an atom there is a small and dense nucleus, made up of protons and neutrons . There is normally quite a few of them, and the number of protons is roughly similar to that of neutrons. Substances are made up of various atoms, which differ in their number of protons. An important point for us is that the proton has a special property called charge .
Charge is a basic quantity underpinning all electrical phenomena.
Charge in a proton is conventionally denoted as positive, and as a result the nucleus is positively charged. In addition to protons and neutrons, an atom has electrons . The number of electrons in atoms is equal to the number of protons 1.2 . Electrons are lighter than protons, and also have the property of charge , which is negative and equal to that of a proton. An atom is made up of a positively charged nucleus and several electrons nearby.