Question

Which among the following has the tendency to form the covalent compounds?
A. Ba
B. Be
C. Mg
D. Ca

Answer 1

Hint:The given element barium, beryllium, magnesium and calcium all belong to the IIA group. The covalent character shows the nature of the element to form the covalent bond with the other element. Covalent bond is formed when two elements share their valence electrons with each other.

Complete answer:
As we move from top to bottom in the group in the periodic table the covalent character decreases and ionic character increases as the atomic size of the element increases, due to this the electrons move away from the nucleus and the attractive forces between between the positive charge of the nucleus and the electron with the negative charge decreases. This results in the easy sharing of electrons by the element to the other element to form the covalent bond.
As the given element barium, beryllium, magnesium and calcium all belong to the IIA group. The beryllium is present at the top of the group, so it will show the highest covalent character from barium, magnesium and calcium.
Beryllium due to its small size, it contains only two electrons in the valence shell. Due to its high polarizing power it shares its two electrons with the other element to form covalent bonds.
Therefore, the correct option is B.

Note:
The covalent character is also dependent on the electronegativity difference, the smaller is the electronegativity difference between the atoms, more covalent bond is formed.