discuss the position of hydrogen in modern periodic table?

  • In the periodic table the position of hydrogen is ambiguous
  • But it is placed at the top of group 1 above the alkali metals. This is because the electronic configuration of hydrogen is similar to alkali metals. Both have 1 valence electron each. 
  • However because of its small size the properties of hydrogen do not match with the alkali metals. 
  • Sometimes hydrogen is not included in any group of the periodic table and it is treated as a special element.

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Hydrogen is placed in the 1st slot in the modern periodic table as it atomic number is 1. It is placed in a group in which all the elements (Li, K, Na, Fr, etc.) have valency 1(+). However, while studying the 1st group, it is not included. Hydrogen also has properties similar to the elements in the group having the haolgens (Cl, I, Br, etc.).

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 Position of an element in periodic table depends upon its electronic configuration and properties. Hydrogen resembles the elements of group I-A, IV-A and VII-A in some respects. Properties of hydrogen do not completely match any one of the above-mentioned groups. That is why position of hydrogen is still undecided.In the coming lines we will discuss why hydrogen can not be placed in a particular group in the periodic table.Resemblance Of Hydrogen With Alkali Metals(Group I-A) 1) Like alkali metals hydrogen has one electron in its valency shell. Explanation H (Z=1): K1Li (Z=3): K2, L1Na (Z=11): K2, L8, M1

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one of the main failiure of the periodic table is that it fail to give a correct place to hydrogen.

Hydrogen has resemblance to properties of both halogens and alkali metals. resemblance can

be seen frm the fact that hydrogen exists only as diatomic molecule which is the main property

of halogens. resemblance to alkali metals can be seen that hydrogen usually exhibit +1(partial)

oxidation state as like alkali metals. SO hydrogen cannot be placed on alkali metals group or in

halogens group.So it is good that hydrogen is placed between the both halogens and alkali metals.

And I have seen in the Modern Periodic Table(Long Form) that hydrogen appears both in alkali

metals group and halogens group.

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Hydrogen is considered as a very unique element.The position of this small element in the periodic table is debatable.

Hydrogen’s position was not justified in the very old Mendeleev’s periodic table. He positioned hydrogen in the first column above alkali metals. He did so because hydrogen and alkali metals have similar properties. For example, hydrogen reacts with halogens, oxygen, and sulphur to form compounds whose formulae are similar to those of alkali metals.

Hydrogen also resembles halogens in many ways. Like halogens, hydrogen is a gas, and exists as a diatomic molecule (H 2 ). It forms covalent compounds like halogens unlike alkali metals. Hence, it can also be placed above the halogen group.




hope u r clear now....:)

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