The atomic number (Z) of an element refers to the number of protons in the nucleus of an atom. It determines the identity of the element.
Isotope: Isotopes are atoms of the same element that have different numbers of neutrons in their nuclei.
Periodic Table: The periodic table is a tabular arrangement of elements based on their atomic numbers and chemical properties.
Electron Configuration: Electron configuration refers to how electrons are arranged in energy levels around an atom's nucleus.