Periodic table is a way to list elements. It is called periodic because elements are lined up in cycles or periods. At first glance, it looks very complex. This listing is done according to the structure of their atoms. It is decided on the basis of number of protons and electron in their outer shell. All the elements are listed in the order of their atomic number, which is same as the no. of protons in each atom. Elements are listed in order of increasing atomic number.
Fun Facts: –
- The Periodic Table was first proposed by Russian chemist Dmitri Mendeleev in 1869. Mendeleev’s table contained 63 known elements.
- Now it contains 109 different elements. Each element is of unique type.
- Mendeleev’s periodic table had some blank spaces for some unknown elements. And he predicted the weights and chemical behaviour of those missing elements correctly.
- Most of the elements are metals.
- 90 of the 109 elements are found in nature and 19 are only created in laboratories.
- The rows of the periodic table are called periods and columns are called groups.
- There are total 18 groups in the periodic table.
- Atoms with atomic numbers higher than 92 do not exist. However, they can be created in laboratory by bombarding elements with other elements or their pieces.
- Technetium was the first element to be made artificially.
- An element’s period number is the highest unexcited energy level for an electron of that element.