Why do metals have body-centered, face-centered, and hexagonal-centered structures?

Consider the four elements above. which one of these elements will combine with oxygen in a 1: 1 ratio?

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.

Water is initially present in a state where its molecules are far apart. during a change of state, its molecules slow down. which change of state has most likely taken place? from a gas to a liquid from a liquid to a gas from a solid to a liquid from a gas to a plasma