Molecules and atoms.

 

A molecule is two or more atoms together.

The atoms are the smallest particles that make up all matter. All that exists in the Universe consists of the combination of atoms. There are in total 118 types of atoms. Each type of atom is known as element. Elements are for example the iron, the lead, the oxygen, nitrogen, mercury, etc.

The water is for example a molecule that consists of two hydrogen atoms and one of oxygen (dihydrogen monoxide).

How big is an atom?

Draw a line of 1 mm long in your notebook.

Divide that line in one thousand equal parts. Each part (segments) is known as micron.

Now divide a micron in 10,000 equal parts. Here you have the size of an atom.