A Level Physics Practice Exam 2026 - Free A Level Physics Practice Questions and Study Guide

An atom is composed of a positively charged nucleus that contains protons and neutrons, surrounded by electrons that are negatively charged. The nucleus, made primarily of protons, which contribute to the positive charge, and neutrons, which have no charge, makes up the central part of the atom. The electrons, which exist in different energy levels or orbitals, are attracted to the nucleus due to the electrostatic forces between the opposite charges.

This fundamental structure of an atom explains the balance between these charged particles and the stability of atoms. The presence of electrons surrounding the nucleus allows for chemical bonding and reactions, necessary for the formation of molecules and the matter we observe in the universe. Therefore, stating that an atom contains a positively charged nucleus and surrounding electrons accurately captures the key components that make up the structure of an atom.