Chemistry is the scientific study of the properties and behavior of matter. It is a natural science covering the elements that makeup matter to the compounds composed of atoms, molecules, and ions: their composition, structure, properties, behavior, and the changes they undergo during a reaction with other substances.
The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity.
The six naturally occurring noble gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn).
A pnictogen is one of the chemical elements in group 15 of the periodic table. This group is also known as the nitrogen family. The chalcogens are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family.
Pnictogens consist of the elements nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and perhaps the chemically uncharacterized synthetic element moscovium (Mc).