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Property of h2 which does not resembles with alkali metal is

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Hydrogen shows properties similar to both alkali metals and halogens, then why is it placed in first group?

Hydrogen shows properties similar to both alkali metals and halogens, then why is it placed in first group?

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GSENVIRO | CERTIFIED EDUCATOR

While hydrogen has properties similar to alkali metals and properties similar to halogens, owing to its unique characteristics, hydrogen is considered neither an alkali metal nor a halogen. It is placed in group I solely because of its electronic configuration with one electron (electron configuration is the arrangement of electrons in orbital shells). It has 1 proton (the most common isotopic form) thus an atomic number of 1 (the number of protons equals the atomic number). The periodic table arranges elements according to their atomic number and electronic configuration, which are the two factors explaining the reason for the position of hydrogen at the top of group I: atomic number and electronic configuration.

Hydrogen shares some properties of alkali metals and halogen, yet it is neither. Similar to alkali metals, hydrogen has 1 electron in its outermost shell and can form compounds with non-metals (such as HCl, etc.). However, it has non-metallic character, is a gas (while alkali metals are solid) and cannot lose its valence electron. Hydrogen is also similar to halogens, since it forms diatomic molecules (H2, same as halogens- Cl2, etc.), needs one more electron to completely fill its outermost shell, etc. However, it is not entirely a halogen either. 


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