The electrostaticattraction between positive and negative ions
Ionic compounds are solid at room temperature with highmelting and boiling points because a large amount of energy is needed to break the strong electrostaticforces of attraction holding the opposite ions together.
Ionic compounds cannotconduct electricity when solid because the ions are in a fixedposition.
Ionic compounds when dissolved in water or molten are goodconductors as ions are free to move so electricity can flow.
Ionic compounds are soluble in polar solvents.
Covalent Bonding
Strongelectrostatic attraction between a shared pair of electrons and the nuclei of bonded atoms.
Giant Covalent Lattices
Many atoms bonded together by covalent bonds. (Diamond/Graphite/Graphene)