What is the oxidation number of hydrogen in CaH2?

What is the oxidation number of hydrogen in CaH2?

• A. +1
• B. 0
• C. -1
• D. +2

Answer: (C)

In the compound calcium hydride (CaH2), the oxidation number of hydrogen is considered to be -1. This is because hydrogen typically has an oxidation state of +1 when bonded to nonmetals, but in this case, it is bonded to calcium, which is a metal. In ionic compounds formed between metals and hydrogen, hydrogen can exhibit a -1 oxidation state. Calcium is an alkaline earth metal and typically has an oxidation state of +2. To maintain electrical neutrality in the compound, the two hydrogen atoms must collectively have an oxidation state of -2 (since +2 from calcium requires -2 from hydrogen). As there are two hydrogen atoms, each must therefore have an oxidation state of -1. This context is important for understanding how oxidation states work in ionic compounds, especially when nonmetals are excluded from bonding relationships with hydrogen.

In the compound calcium hydride (CaH2), the oxidation number of hydrogen is considered to be -1. This is because hydrogen typically has an oxidation state of +1 when bonded to nonmetals, but in this case, it is bonded to calcium, which is a metal. In ionic compounds formed between metals and hydrogen, hydrogen can exhibit a -1 oxidation state.

Calcium is an alkaline earth metal and typically has an oxidation state of +2. To maintain electrical neutrality in the compound, the two hydrogen atoms must collectively have an oxidation state of -2 (since +2 from calcium requires -2 from hydrogen). As there are two hydrogen atoms, each must therefore have an oxidation state of -1.

This context is important for understanding how oxidation states work in ionic compounds, especially when nonmetals are excluded from bonding relationships with hydrogen.