Which of the following species determines the chemical properties of an atom?

The species that determines the chemical properties of an atom is the electron. This is because electrons are responsible for the bonding of atoms with each other, which determines the chemical properties of a substance. Electrons are negatively charged particles that orbit around the nucleus of an atom. The number of electrons in the outermost shell (valence shell) of an atom determines how it will interact with other atoms, forming chemical bonds. The chemical reactivity and behavior of an atom depend on its valence electrons, which determine the atom's ability to form chemical bonds with other atoms. Therefore, electrons play a crucial role in determining the chemical properties of an atom.