Chapter 21, Problem 19PS

Interpretation Introduction

Interpretation:

The element that does not react with hydrogen among the following has to be predicted.

Concept introduction: The reaction of elements with hydrogen produces either ionic metal hydrides or molecular compounds.  The reaction of hydrogen with metals produces ionic metal hydrides. The electronegativity of hydrogen is more than metals and hence, metals bears positive charge and hydrogen has negative charge. Thus, the oxidation number of hydrogen in ionic metal hydrides is $-1$. The reaction of non-metals with hydrogen produces molecular compounds. In general, non-metals are more electronegative than hydrogen and hence, hydrogen bears positive charge and non-metals are negatively charged in molecular compounds. Thus, the oxidation number of hydrogen in molecular compounds is $+1$.

The oxidation number of metals in ionic hydrides and non-metals in molecular compounds are according to the group number and valence electron configuration of these elements.

So, hydrogen react with both metals and non-metals to produce hydrides of corresponding elements. However, the elements belonging to noble gas family have very low chemical reactivity and therefore do not combine with hydrogen.