Question

Why do hydrogen and lithium react differently?

Answer 1

▪︎Hydrogen is not an alkali metal itself, but has some similar properties due to its simple one proton, one electron arrangement. For lithium, there are two 1 s electrons in an inner orbit and one 2 s electron in the outer orbit. The same pattern holds for sodium and potassium.

▪︎All the alkali metals react with hydrogen at 673 k except lithium reacts at 1073 k. Due to small size and high charge to size ratio large amount of energy would be needed to form covalent bond in LiH.

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