Скачать или смотреть The Periodic Table : Class 6-10

What is a periodic table and how are elements formed?
As we know, Elements are made up of atoms. Each atom contains a specific amount of protons, neutrons and electrons which determine the characteristics of the element. There are around eighty-six elements that are found in nature. It is said that they were formed during nuclear reactions that took place in huge stellar explosions of stars called as supernova. That is during The Big Bang only a few light elements were formed. Stars were formed only when the cosmetic dust and gases from The Big Bang cooled down which then grouped to form galaxies.

The first periodic table was published in the year 1869 by Dmitri Mendeleev. He stated how elements were added according to the atomic weight a pattern that resulted when properties for elements recurred periodically. Later, Henry Moseley, a physicist rearranged the periodic table based on the increasing atomic number such that it was easy to predict the various properties of elements that were yet to be discovered.

Each element in the periodic table is represented on the basis of their atomic number that illustrates the number of protons present in its nucleus. According to their atomic numbers and electronic configurations, these elements are placed accordingly into a tabular arrangement of rows and columns wherein elements in the same column (group) have similar properties due to their similar valence shell configuration.

Essentially in this tabular arrangements we have metals on the left side of the table and nonmetals on the right side. In detail, the elements have been divided into blocks which are : Alkali metals, Alkaline earth metals, Lanthanides, Actinides, Transition metals, Post Transition metals, Polyatomic nonmetals, Diatomic nonmetals and Noble gases.

But the above subdivisions are not enough to cater information on every element we know of. Quite a number of elements comprises of variations in the number of neutrons but with the same number of protons, that is having the same atomic number but varying mass numbers. This variation leads to different types of forms of the same element which we term as isotopes. There is no separate column for an isotope in the periodic table. They are grouped or placed together under the same element.

Have a brief introduction into the elements and their properties in the periodic table with this interesting video module.

Explore more about periodic table at: https://byjus.com/periodic-table/

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