PERIODIC TABLE

The periodic table is an arrangement of chemical elements in the order of their atomic number, electron configurations and recurring chemical properties in a tabular form.

The modern periodic table has eighteen vertical columns called groups and seven horizontal rows called periods. Elements are arranged in the order of increasing atomic numbers and show the trends in their properties.

The periodic table serves the following purposes:

1. It an be used to derive relationships between the properties of the elements.

2. It can be used to predict properties of new elements yet to be discovered or synthesized.

3. It provides a useful framework for analysing chemical behaviour.

GROUPS

As mentioned above, the periodic table has eighteen vertical columns called groups and they are arranged from the left to the right.

Group 1: These elements are known as Alkali metals (except hydrogen) as they form strong alkalis with water.

Group 2: These elements are known as Alkali earth metals. They form weaker alkalis with water as compared to group 1 elements.

Groups 3 to 12: The elements in these groups are known as transition elements. All the elements of these groups are called metals. They have their two outermost shells incomplete.

Group 13: Boron family – Boron is the first member of the group.

Group 14: Carbon family

Group 15: Nitrogen family

Group 16: Oxygen family, also known as chalcogens, meaning ore forming.

Group 17: These elements form salts and hence they are known as Halogens, meaning salt formers.

Group 18: This group is known as Zero group. Elements of this group are called the noble gas or inert gas.

The elements of the groups 1, 2, 13, 14, 15, 16 and 17 have 1, 2, 3, 4, 5, 6 and 7 electrons in their outermost shells respectively. They are known as the main group elements or representative elements or normal elements. The outermost shells of the elements of these groups are incomplete.