Density involves the amount of a material in a certain volume. when a material changes phases, it changes in density in a predictable way as the amount of material stays the same but the molecules get farther apart or closer together. water has solid and liquid states that do not follow these predictions of density in the phases of matter. what does that mean about the densities of the phases of water?

Because the density of water does not act in the same way as other medium it is an anomaly ( meaning it deviates from what is expected.)

This is called an anomalous trend.

for the points

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.