Nonmetals and metals have the same atomic structure. Electrons follow paths called orbits around a central core called a nucleus. Atoms are stable when all electrons are paired, so most metals and nonmetals do not exist in nature in pure form.
Orbital arrangement remains the same. The formula, 2 times (n) squared, where n is the number of the orbital, defines the number of electrons that can exist at each level.
Metals and nonmetals that have an odd number of electrons will attract other metals or nonmetals that need an electron. They share electrons, forming a molecule. For example, the nonmetallic molecule, water, contains two atoms of hydrogen and one atom of oxygen, and the metallic mineral galena contains one molecule of lead and one of sulfur.
Whether the atom is a metal or a nonmetal, it contains a unique number of protons in its nucleus. Scientists use this unique number, called the atomic number, to assign the substance a place on the periodic table of elements.
Metals and nonmetals have measurable or observable characteristics, like shape, color, density odor, taste, hardness, boiling point and melting point. Even when they combine with another substance and form a molecule, scientists expect certain characteristics to occur that distinguish that compound from another.