Matter is anything that occupies space and has weight. It may be found in any one of three states: solid, liquid, or gas.
An element is the basic building block of nature. It is a substance that cannot be reduced to a simpler substance by chemical means. Examples of elements are gold, silver.
The chemical combination of two or more elements is called a compound . A compound can be separated by chemical, but not by physical means. Examples of compounds are water, which consists of hydrogen and oxygen, and salt, which consists of sodium and chlorine.

The smallest part of the compound that still retains the properties of the compound is called a molecule.
A molecule is the chemical combination of two or more atoms.
An atom is the smallest particle of an element that retains the characteristic of the element. The physical combination of elements and compounds is called a mixture. Examples of mixtures include air, which is made up of oxygen, nitrogen, carbon dioxide, and other gases, and salt water, which consists of salt and water.
All matter is made of atoms; and all atoms consist of electrons, protons, and neutrons. The configuration of certain electrons in an atom is the key factor in determining how well a conductive or semiconductive material conducts electric current.
References :
- Introduction to Basic Electricity and Electronics Technology By Earl Gates
- Electronics Fundamentals Circuits, Devices and Applications BY Thomas L. Floyd and David L. Buchla