What do the properties of elements depend on?

The properties of elements are fundamentally determined by their atomic structure and atomic number. The atomic structure encompasses the arrangement of protons, neutrons, and electrons within an atom. The atomic number, which is the number of protons in an atom's nucleus, uniquely identifies each element and defines its position on the periodic table.

The atomic structure directly influences the element's chemical properties, such as how it reacts with other substances, its electronegativity, and its ionization energy. For instance, elements with similar atomic numbers often exhibit similar chemical behaviors due to their electron configurations. This is evident, for example, in groups of elements in the periodic table, such as the alkali metals, which have the same number of electrons in their outer shell, leading to similar reactivity.

While the arrangement in the periodic table provides valuable insights into elemental properties, it is the atomic structure and number that ultimately dictate these characteristics. Chemical reactions and physical states are also influenced by these underlying factors but do not define the intrinsic properties of the elements themselves.