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( ionic, covalent, diatomic ) compounds conduct ( electricity, charges, protons ) when molten or in ( liquid, an aqueous solution, a solid ) but not when solid. the ions in a liquid are free to ( move, leave the molecule, gain electrons ) and carry ( a charge, electrostatic current, protons ) but in a solid the ions are in a ( fixed position, complicated relationship, number of positions ).
ionic compounds have ( high, low, reasonable ) melting points. ( giant ionic lattices, giant metallic lattices, giant covalent structures ) are held together by ( strong electrostatic forces, weak elctrostatic forces, weak intermolecular forces ). it takes a ( lot of energy, small amount of energy, big force ) to overcome these forces, so melting points are very high.
ionic compounds tend to ( dissolve, become ionic, react ) in water. water molecules are ( polar, negative, diatomic ) -part of the molecule has a small negative charge and other bits have small ( positive, weak, negative ) charges. these charged parts ( pull away, react, become completely detached ) from the lattice, causing it to dissolve.