What structural units make up ionic solids

The answer is ions. These ions are cations (positively-charged ions) and anions (and negatively charged ions) that are attracted to each other by electrostatic forces due to their charges. They are held up in alternating sequence (that is usually geometric) in a lattice/crystal structure.

Answer: Ions make up the ionic solid.

Explanation: Ions are the structural units or in other words, it can be said that they are the building blocks of the ionic solids.

When negatively charged ion comes in contact with the positively charged ion, they will held each other through electrostatic forces of attraction and thereby forming a bond.

Thus there will be a regular pattern of these ions to form a electrically neutral ionic solid. There can be a positively charged or the negatively charged ionic solid as well when the presence of the respective ions increases.