Question

Use data in this chapter and Chapter 12 to discuss why MgO is an ionic compound but CO is not an ionic compound.

Short answer

Due to significant difference between electronegativity of Mg and O, they form an ionic bond. But in CO, the electronegativity difference between C and O is not very large. Thus they form covalent bond by mutual sharing of electrons.

Step-by-step solution

- Determining the MgO:

In the case of the MgO compound, magnesium is a metal atom that belongs to the alkali group and oxygen is a nonmetal that belongs to the p-block group. So, magnesium metal transfers its electrons whereas oxygen atoms will accept it and a bond will form between them which is called an ionic bond.

- Determining that how magnesium metal is transferring its electron:

The magnesium metal is transferring its electrons and oxygen as a nonmetal accepting the electrons, and both these formed ${\mathrm{Mg}}^{+2}$and ${\mathrm{O}}^{-2}$ions which are held together by the electrostatic force of attraction, and an ionic bond forms between them.

- Determine the CO compound:

CO is a covalent compound, as firstly, it consists of a double covalent bond and a single coordinate covalent bond (in total, 3 covalent bonds), between carbon and oxygen atoms. Secondly, due to a small difference of electronegativities of carbon and oxygen atoms (∆E=1.0), these atoms settle upon sharing of electrons.