Question

Among CaH₂ , BeH₂ , BaH₂ , the order of ionic character is

• A. BeH₂ < CaH₂ < BaH₂
• B. BeH₂ < BaH₂ < CaH₂
• C. CaH₂ < BeH₂ < BaH₂
• D. BaH₂ < BeH₂ < CaH₂

Answer 1

The Correct Option is A

To determine the order of ionic character among the hydrides CaH₂, BeH₂, and BaH₂, we need to consider the concept of electronegativity difference and the position of elements in the periodic table:

1. The ionic character of a compound is related to the difference in electronegativity between the metal and hydrogen in the hydride. The greater the difference in electronegativity, the more ionic the hydride.

2. In the periodic table, as we move down the group, the size of the metal atom increases, which generally decreases the electronegativity of the metal. Therefore, the ionic character also increases because the electropositive character increases.

3. Let's compare the electronegativity and ionic character of the three hydrides:

   • BeH₂: Beryllium (Be) is in the second period and has a relatively high electronegativity for a metal, making BeH₂ less ionic, due to a lesser difference in electronegativity between Be and H.
   • CaH₂: Calcium (Ca) is located below Be in the periodic table and has a lower electronegativity than Be, making CaH₂ more ionic than BeH₂.
   • BaH₂: Barium (Ba) is located below Ca, being even less electronegative than Ca, making BaH₂ the most ionic of the three hydrides.

4. Therefore, the order of increasing ionic character is: BeH₂ < CaH₂ < BaH₂.

This analysis shows that the correct answer is: BeH₂ < CaH₂ < BaH₂.