So nonmetals represent the second largest classification for elements, so they're the ones shaded in blue like we set up above. Now, a key way to remember the physical properties of nonmetals is in comparing them to metals. Just remember here that nonmetals tend to have the opposite trend of metals when it comes to their physical properties.
Metals have a luster, they're shiny. Nonmetals are dull. Metals are good conductors, but nonmetals are poor conductors. Metals are opaque because they're not see through, but nonmetal. Some of them are transparent and see through. And then finally, we said that metals have a malleability where we can hammer them without them falling apart.
The opposite of being malleable is being brittle. If you were trying to hammer some nonmetals, they would literally crumble in your hands. So just remember, if you can remember the physical properties of metals, nonmetals are basically the opposite trend.