Physics – 5.1.1 The atom | e-Consult

An atom is the basic building block of matter. At its centre lies the nucleus, which is a dense, positively charged region. The nucleus is composed of protons, which carry a positive charge (+1), and neutrons, which have no charge (neutral).

Orbiting the nucleus are electrons, which are negatively charged (-1). These electrons exist in specific energy levels or shells around the nucleus. The number of electrons in a neutral atom is equal to the number of protons in the nucleus, resulting in a balanced overall charge.

The positive charge of the nucleus attracts the negatively charged electrons, holding them in orbit. This electrostatic attraction is the primary force maintaining the atom's structure. The strong nuclear force holds the protons and neutrons together within the nucleus, overcoming the electrostatic repulsion between the positively charged protons.