Question

The most ionic compound among the following is:
(A) Silica
(B) Aluminum fluoride
(C) Carborundum
(D) Aluminum chloride

Answer 1

The compounds in which the atoms have higher difference between their electronegativities are ionic compounds. Electronegativity of the atom increases as its negative charge per volume increases in its ionic form.

Complete step by step solution:
We are given a few compounds and we will find which one of them is the most ionic.
- Ionic bonds are formed by the attraction of the negative and positive ions. We know that more the charge density of those ions, more ionic the compound will be.
- The compounds that involve atoms which have a tendency to share the electron rather than lose or gain them to form ions form covalent bonds.
A) $Si{O_2}$ (Silica)
Silica has silicon in its structure. Silicon is a carbon family element and it also forms covalent bonds rather than ionic bonds. So, silica is a covalent molecule.
B) $Al{F_3}$ (Aluminum Fluoride)
Aluminum is a metal that is an electropositive element. Fluorine is the element which has highest electronegativity. So, the Al-F bonds will be ionic and this molecule will be most ionic.
C) SiC (Carborundum)
As we saw earlier that both carbon and silicon have a tendency to form covalent bonds. So, here in these molecules, the bonds will be highly covalent. So, this molecule is most covalent and least ionic.
D) $AlC{l_3}$ (Aluminum chloride)
This molecule is also an ionic molecule. Here, chlorine atoms are less electronegative than fluorine atoms. So, $AlC{l_3}$ is less ionic than $Al{F_3}$ molecule.
So, we can conclude that $Al{F_3}$ is the most ionic molecule.

Therefore, the correct answer is (B).

Note: The elements that can easily lose or gain electrons to attain noble gas configuration have a tendency to make ionic bonds. The other elements will share the electrons and form covalent bonds.