why does copper shrink when it cools down?

Question

something with the molecules?

Answer 1

Many things expand when heated and shrink when they cool. One exception, though, is water. It expands as it freezes.

Answer 2

Everything shrinks when it cools down (except water, up to a certain point). Heat excites molecules -- increases their vibration, so that they move farther apart and the material becomes less cohesive, "softer", eventually becoming a liquid or a gas. Molecules lose energy when they radiate heat away and vibrate more slowly (become less excited). Then the normal molecular bonds are strengthened and the material becomes more compact.

At least that's the general idea.

Answer 3

doesn't everything shrink when they cool down?