Atoms and Molecules

Atoms

Elements are made of tiny particles called atoms. The atoms of one element are not the same as the atoms of another element.

Atoms- are the smallest particles of an element that have the chemical properties of that element.

*Each atom of an element is represented by the element's symbol.

1 atom in an element

Helium, neon, argon, krypton, xenon and radon are the only elements that existas individual atoms. They are monatomic elements. This means that their atoms are not joined together chemically.

Molecules

A group of two of more atoms that are chemically combined

H2 is used to represent a hydrogen molecule. H2 us the molecular formula of hydrogen.

(2 hydrogen atoms chemicallly combined)

O3 (ozone molecule) is 3 oxygen molecules chemically combined.

Types of molecules

• diatomic molecules (two atoms chemically combined)

          -helium, argon

• triatomic molecules (three)
• polyatomic (four or more)