Atomic structure refers to the arrangement of subatomic particles within an atom. Atoms consist of a central nucleus, which contains positively charged protons and neutral neutrons. Surrounding the nucleus are negatively charged electrons that orbit in specific energy levels or shells. The number of protons in the nucleus determines the element's identity, while the number of neutrons can vary, leading to different isotopes of the same element. The balance between protons and electrons affects the atom's overall charge, resulting in neutral atoms or charged ions. Understanding atomic structure is fundamental to the study of chemistry and physics.