Modern Periodic Table or Long Form of Periodic Table:

In the Modern Periodic Table, the elements are arranged in increasing order of their atomic numbers.

The Modern Periodic Table was formulated by Henry Moseley in 1913.

Modern Periodic Law: It states that “the properties of elements are a periodic function of their atomic numbers.”

Main Features of Modern Periodic Table

• The elements are arranged according to their electronic configurations.
• There are seven periods, numbering 1 to 7. The period number signifies the number of electron shells of an element. Thus, the period one elements have only one shell. The period two elements have only two shells, and so on. Period 1 is the shortest period with only two elements. Periods 2 and 3 are short periods with eight elements each. Periods 4 and 5 are long periods.