THE MODERN PERIODIC TABLE

The periodic tabel shown above is an example of modern periodic table know as lonf form of periodic table.It is divided into 18 groups and 7 periods.It is based on the magic number 2,8,8,18 and 32 after which their properties get repeated.
All elements of the same group have equal no of valence electrons,valency,chemical properties,melting and boiling points.The elements of the group 18 are non-reactive.The atomic radii of the elements of the same group increase down the group.
There are 2 elements in the first period known as very short period.We find 8 elements in the 2nd and 3rd periods each called short periods.4th and 5th periods have 18 elements each known as long periods.6th and 7th periods have 32 elements each called long periods.Atomic radii of the elements decrease from left to right .Along a period the metallic character of the elements decrease while the non-metallic character increase.

Tarbej Ansari