Metals have a giant structure. The atoms are arranged in regular layers, and each atom gives up its outer electrons to form a positive ion. The metallic bonding is the strong electrostatic attraction between the positive ions and the sea of delocalised electrons that move freely between them.
Metals conduct electricity because the delocalised electrons are free to move through the metal and carry an electric charge. They also conduct heat well, because the moving electrons pass on energy. Metals have high melting points because a lot of energy is needed to overcome the strong attraction between the ions and the electrons.
Metals are malleable, which means they can be hammered or bent into shape without breaking. The layers of positive ions can slide over each other, and the delocalised electrons keep holding the ions together as they move.
