In the diagrams presented in the other three sections, the points show where atoms would lie if there were no motion due to heat; that is, if the metal's temperature were at absolute zero (-273°C).
When a liquid metal cools and turns into a solid, its atoms come together to form crystals. The structure of these crystals is not perfect. Sometimes an extra layer of atoms squeezes between other ...
A model showing how metallic bonds are formed - the first diagram shows the outer electrons in their atoms, and the second diagram shows that the electrons have become delocalised ...