1. Periodic Table of Elements

2. All matter is composed of atoms.
Atoms are made up of small particles (subatomic particles) called:
protons (that are located in the nucleus of the atom and have a positive charge),
neutrons (that are located in the nucleus of the atom and have no charge) and
electrons (that are located in energy shells surrounding the nucleus of the atom and have a negative charge)..

3. Each element is represented by its own unique chemical symbol.
Chemical symbols consist of either one or two letters.
These symbols are based on either English or Latin names of the elements.

4. The periodic table of elements is a grouping of elements in order from smallest to largest (left to right) and lightest to heaviest (top to bottom).
The elements are arranged in 'families of chemical elements' that share similar physical and chemical properties. These families are arranged in vertical columns in the periodic table and are referred to as groups.

5. The rows from left to right are referred to as periods.
The periodic table also places the elements in order of electronegativity. Electronegativity increases in a regular order from left to right across the periods on the periodic table. Electronegativity also decreases from top to bottom of the groups on the periodic table.

6. It is also divided into metals, metalloids and non-metals.
The metals are located on the left side of the periodic table (except for hydrogen -- which is the only non-metal located on the left side of the staircase line).
The staircase line divides the metalloids into two (except for aluminium which is directly to the left of the staircase line). The non-metals are then located on the right side of the periodic table.

7. The atomic number is the number of protons found in the nucleus of the atom.
The atomic mass is the sum of the number of protons and neutrons in the atom. Because the mass of the electron is so tiny (9.109 3826 x 10-31 kg ), their mass is not included in the atomic mass of an atom

8. A molecule is a particle that has two or more atoms bonded together
A molecule is a particle that has two or more atoms bonded together. The air we breathe contains molecules of oxygen atoms bonded together in pairs. The chemical symbol for the oxygen that we breathe is O2 -- the subscript "2" tells us that there are two atoms of oxygen in each molecule of oxygen.

9. A compound is a molecule that has more than one kind of atom bonded together. These atoms are chemically bonded to each other. Water is an example of a compound. The chemical formula for water is H2O - this means that there are two atoms of hydrogen bonded to one atom of oxygen.

10. The periodic table of elements lists the atomic mass of each element underneath the chemical symbol. The molecular mass (also referred to as the formula mass) of each molecule is determined by adding up the individual atomic masses of each atom that form the molecule.