Question

If argon contains only 1 atom (Ar) how can we call it as a molecule?
because in my text book its given that "MOLECULES of many element such as argon (Ar), helium (He) ..etc are made of only 1 type of atom". If they are made of only 1 tyoe of atom, how can it be callled as a molecule?

Answer 1

Hello dear,
First let us understand the definition of molecule -
A molecule is in general a group of two or more atoms that are chemically bonded together, that is, tightly held together by attractive forces. A molecule can be defined as the smallest particle of an element or a compound that is capable of an independent existence and shows all the properties of that substance.

It says that in general molecule is group of two or more than two atoms, but it could be one atom also in case of Argon, Helium and other noble gases. A single atom of noble particle satisfy the necessary condition of molecule, that it is capable to exist independently and it show all property of that noble gas.
Thus atoms of Noble gases such as Argon, Helium can also be called molecules.