ELEMENTS, COMPOUNDS AND MIXTURES

*ATOMS
Elements are made up of tiny particles called atoms. The atoms of one element are not same as the atoms of another element. To show one atom of an element, chemists use its chemical symbols.
Eg : To show ONE atom of hydrogen, chemists write "H" since the chemical symbol for hydrogen is "H". Atoms are joined chemically to form elements however there are some elements which defy this rule. The elements are Helium, Neon, Argon, Krypton, Xenon and Radon are the only elements that exist as individual atoms which means that their atoms are not chemically joined. They are called MONATOMIC ELEMENTS.
Metals exist asa atoms but large numbers of their atoms are arranged in a special way to form giant structures. Most non-metals exist as molecules.

*MOLECULES
A molecule is a group of tow or more atoms chemically joined together.
Molecules formed by the combination of two atoms is called "diatomic molecules" where as molecules with three atoms are called triatomic molecules and molecules formed by four or more atoms is called polyatomic molecules.