How can we justify the position of Hydrogen in the periodic table? It resembles elements of 1-A and VII-A

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jerichorayel's profile pic

jerichorayel | College Teacher | (Level 2) Senior Educator

Posted on

The location of hydrogen atom in the periodic table has been disputed for long time due to its uniqueness and similarities to other groups of elements. However, recent print outs of periodic tables shows that hydrogen is in group 1A or the alkali group of metals.

Some reasons why hydrogen was placed in the group 1A elements are as follows:

  • It has a valence electron of 1. The valance electronic configuration of hydrogen is the same with the group 1A elements.
  • It can form an ion with a charge of +1
  • Hydrogen and other alkali metals are good reducing agents
  • It forms compounds with non-metals

            Halides (HCl, HBr, HI, HF)

            Group IVA (CH4)

            Group VI (H2O, H2S)

  • Can be metallic at extreme conditions (~250,000 atm)

Here are some limitations with the allocation of Hydrogen in the group 1A metals:

  • Possess a characteristic similar to group VII A (halogens)
  • Can form both ionic and covalent compounds
  • Hydrogen is gas at room temperature while the rest of the metals in group 1A are solid.
  • Also have some similarities with group IVA specifically with carbon and silicon.
rakibulalam's profile pic

rakibulalam | Student, Undergraduate | eNotes Newbie

Posted on

some reasons why Hydrogen was placed in the group VIIA are as follows :

1) non metal

2)twice molecular like halogens

e.g H2 , I2 , F2 etc

3)can make metal hydrydes

 e.g NaH

4) its valency is one like all halogens

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