Every compound has one certain formula and no other. All substances can be frozen if the temperature is low enough. All ionic substances are solids at room temperature, but many covalent polar substances are liquids at room temperature. Many nonpolar substances are gases at room temperature, but some are liquids or even solids. 13 Polar substances dissolve in other polar substances.
Nonpolar substances dissolve in other nonpolar substances.
Polar and nonpolar substances do not dissolve in each other. Some ionic substances dissolve in polar liquids, but some do not. When ionic substances dissolve in water, the solution conducts electricity. But when polar substances dissolve, the solution does not conduct electricity. Elements do not decompose, but all compounds decompose at some temperature.