## Periodic Table of Elements

A Periodic Table is the arrangement of the elements in tabular form according to their properties so that similar elements fall within the same vertical column and dissimilar elements are separated.

To understand the behavior of compounds we need to understand the behavior of atoms. The elements are arranged in tabular form to rationalize diverse physical and chemical properties.

## Mendeleevâ€™s Periodic Law

• The periodic properties of elements are a periodic function of their increasing atomic weights.
• It had 8 groups (vertical columns) and 6 periods (horizontal rows)

## Modern Periodic Law

• The periodic properties of elements are a periodic function of their increasing atomic numbers.
• The modern periodic table has 7 periods and 18 groups.

A repetition of properties is seen after 2, 8, 8, 18, 18, and 32 elements. The numbers 2, 8, 18, and 32 are called magic numbers.

## Periodicity in Properties of Elements

Periodicity is the repetition of elements with similar properties after certain regular intervals when the elements are arranged in order of increasing atomic number.

The periodic repetition of properties is due to the recurrence of similar valence shell configurations after regular intervals.

You can check the summary on the periodicity of the elements in the periodic table here.

## Short period and long period in the modern periodic table

• Periods 1, 2, and 3 have 2, 8, and 8 elements respectively, and are called short periods.
• Periods 4, 5, and 6 have 18, 18, and 32 elements respectively, and are called long periods.