You wake up early in the morning and your room is fairly dark. you look over and see your shirt hanging on a hook. you know it's your red shirt because you hung it up there before you went to bed, but in the dark you can't see its color. it looks dark gray to you. why is that?

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.