And examples include any type of alkali metal or alkaline earth metal. For example, a composite which actually isn't an alkaline or alkali metal, but is a transition metal, but still it's a metal that has a metallic solid structure. Other examples are sodium metal or potassium metal or leafy metal or calcium metal. Any of these guys have a metallic like structure or metallic crystal structure. So now let's look at the third type of Crystalline Solids known as molecular solids. Now, these crystals, or these Crystalline solids consist of molecules held together by intermolecular forces called down their balls forces.