Question

In which of the following species the bonds are non- directional?
A.$$NC{l}_3$$
B.$$RbCl$$
C.$$BeC{l}_2$$
D.$$BC{l}_3$$

Answer 1

Hint: We must have to know that in an ionic bond two opposite charges are present and there is an electrostatic force that is two opposite charges. Hence, the ionic bonds are known as non- directional bonds. The ionic bond is also called electrovalent bonds. And in non- directional bonds, the direction of the bond is not a matter. But in the case of a covalent bond, it is directional. Hence, the attraction is in a particular direction.

Complete answer:
The nitrogen chloride is a chemical compound having the formula, $$NC{l}_3$$. And the bond present in $$NC{l}_3$$ is covalent bond. Because it is moderately a polar molecule due to the presence of lone pairs of electrons in nitrogen, it repels the bond pair of electrons of $$N-Cl$$ bond. Therefore, the bonds are directional. Hence, option (A) is incorrect.
Rubidium chloride is a chemical compound having the formula,$$RbCl$$and it contains rubidium and chlorine ions in the ratio $$1:1$$. The rubidium chloride is formed by ionic bonds. And this ionic compound is formed by the reaction of rubidium and chlorine gas.
The ionic bonds are always non- directional and it does not have any geometry. Here, the electronegativity difference between rubidium and chlorine is greater than 1.7. Therefore, the bond is ionic. Thus, the bonds present in $$RbCl$$ are non – directional. Hence, option (B) is correct.
Beryllium chloride is an inorganic compound having the formula, $$BeC{l}_2$$. And the bond present in $$BeC{l}_2$$ is covalent. Because, the relative ionization of Be is very small and there does not form any cations. Thus, the bonds are directional in $$BeC{l}_2$$ Hence, option (C) is incorrect.
Boron trichloride has a symmetrical structure, thus it is a non-polar compound. And the bond present in $$BC{l}_3$$ is covalent. Therefore, it is directional. Hence, the option (D) is incorrect.

Note:
Among the given compounds, the non- directional bonds are present in rubidium chloride, $$RbCl$$. The non- directional bond implies that it should be non- directional. Because, it does not have any geometry and it will not depend on the direction of a bond. And in the case of rubidium chloride, an ionic bond is present in $$RbCl$$. But the bonds present in the remaining three compounds are covalent. Therefore they are directional.