Question

Group 2 hydrides with significant covalent character is/are
A. BeH₂
B. MgH₂
C. Both A and B
D. None of these

Answer 1

Hint: In this question we have to use the trend of covalent characters of the group 2 of the periodic table. Down the group, the covalent character always gets stronger. This is due to the fact that it is simpler to share electrons with other atoms when the electron cloud becomes farther away from the atom's nucleus. As a result, the covalent character always gets weaker over time.

Complete Step by Step Answer:
Some elements of the s-block, such as Be and Mg, do not produce ionic hydrides. Small size and strong electronegativity cause high polarising power. In a periodic table, covalent character increases from left to right whereas metallic character increases from right to left.

As ∆EN rises, the ionic bond character also does. As delta EN gets smaller, covalent bonds become less polar. As a result, compounds made up of metals from Group 1A(1) and nonmetals from Group 7A(17) have the highest level of ionic character. The most covalent and least polar are those composed of elements (nonmetals) in Groups 6A(16) and 7A(17). The majority of Groups 1A and 2A element-based materials are metallic.
The correct answer is C.

Additional Information: We are aware that a substantial electronegativity difference between the hydrogen and metal atoms is necessary for the formation of an ionic hydride complex. Ionisation energies of both magnesium and beryllium can also contribute to the covalent character of the magnesium and beryllium hydrides. Beryllium and magnesium currently have electronegativities of 1.57 and 1.31, respectively. These values are quite near to hydrogen's electronegativity of 2.20. As a result, the Be and Mg hydrides are not ionic in nature. Ionisation energies: Be and Mg have the highest ionisation energy of all the group 1 and group 2 elements, making it challenging to ionise them. So, the nature of hydrides of Be and Mg will be covalent.

Note: The formation of covalent compounds occurs when the electronegativities of the two atoms are identical. Ionic bonds are created when electrons are transported from the metal atom to the non-metal atom, whereas covalent connections are created when the electrons are shared between the two atoms.