. Justify the position of hydrogen in the periodic table on the basis of its electronic configuration


Best Answer

Answer: Resemblance with alkali metals:

l. Like alkali metals, hydrogen contains one valence electron in its valence shell.

H : 1s1

Li : [He] 2s1

Na : [Ne] 3s1

Hence, it can lose one electron to form a unipositive ion.

2. Like alkali metals, hydrogen combines with electronegative elements to form oxides,halides, and sulphides.

Resemblance with halogens:

1. Both hydrogen and halogens require one electron to complete their octets.

H : 1s1

F : 1s22s22p5

Cl : 1s22s22p63s23p5

Hence, hydrogen can gain one electron to form a uninegative ion.

2. Like halogens, it forms a diatomic molecule and several covalent compounds. Though hydrogen shows some similarity with both alkali metals and halogens, it differs from them on some grounds. Unlike alkali metals, hydrogen does not possess metallic characteristics. On the other hand, it possesses a high ionization enthalpy. Also, it is less reactive than halogens.

Owing to these reasons, hydrogen cannot be placed with alkali metals (group I) or with halogens (group VII). In addition, it was also established that H + ions cannot exist freely as they are extremely small.  They always associated with other atoms or molecules. Hence, hydrogen is the  best placed separately in the periodic table.

 

 

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