An atom is the fundamental structure of an element. A typical atom consists of a nucleus of positively-charged protons and electrically neutral neutrons with negatively-charged electrons orbiting this nucleus

Amoleculeis the smallest particle in a chemicalelementorcompoundthat has the chemical properties of that elementorcompound.Moleculesare made up ofatomsthat are held together by chemical bonds.

A compound is a substance that results from a combination of two or more different chemical element s, in such a way that the atom s of the different elements are held together by chemical bonds that are difficult to break.

Atomicity is the total number of atoms present in one molecule of an element, compound or a substance

Valencyis the combining power of anelement. Thevalency of an elementis related to how many electrons are in the outer shell.

where is the answer of mixture

A mixture is defined as the result of combining two or more substances, such that each maintains its chemical identity. In other words, a chemical reaction does not occur between components of a mixture. Examples include combinations of salt and sand, sugar and water, and blood.