1. All existing matter in our surroundings is made up of basic units known as elements. Initially, in 1800, only 31 chemical elements were discovered. After some advancement in technology in 1865, about 63 more elements were discovered. This created the need for the periodic classification of elements

Presently, there are 118 elements known to us. Out of these 118 chemical elements, some of the elements are man-made.

There are 4 blocks in the periodic table. The blocks are:

s-block

• p-block
• d-block
• f-block

All the elements in a block are very similar but each one is slightly different than the other. All of the s-block elements are metals. Generally they are shiny, silvery, good conductors of heat and electricity, and lose their valence electrons easily. The p-block has the biggest variety of elements and is the only block that contains three types of elements: metals, nonmetals and metalloids.  D-block elements have properties that are between between s-block elements and p-block elements properties. They are more electropositive than p-block elements but less electropositive than s-block elements. The F-block elements are mostly radioactive elements.

The block names were created to represent the quality of the spectroscopic lines (the electromagnetic radiation absorbed and emitted by atoms) of the atomic orbitals.