Metallic substances have a number of characteristic properties. They're malleable, they conduct electricity well, they conduct heat well, and they also have that shiny metallic luster that is so recognizable. Let's look at malleability first. Malleability means that a substance can be beaten into shape or it can be deformed without breaking. This property was what allowed the ancient Vikings, Romans and other civilizations to make gold jewelry and bronze and iron weapons and tools with very simple methods. The reason for the malleability of metals is that when a metal lattice is disturbed, although the lattice of positive ions may shift out of shape, the sea of electrons is able to flow between the ions and maintain the electrostatic attraction. This allows the lattice to be greatly deformed without it breaking. This is in contrast to the ionic lattice, which relies on the attraction of neighboring oppositely charged ions. If an ionic lattice is deformed so that these oppositely charged ions are no longer neighbors, the electrostatic attraction is lost. Metals also conduct electricity well, although some are better conductors than others. This is why we use metals to make wires and to build electrical circuits. For electricity to be conducted through a material, charged particles must move from one place to another. In a metal, the de-localized valence electrons in the metal lattice are able to move through the lattice, and this allows metals to conduct electricity. Note that this is different to ionic substances. When salts are liquid or dissolved, it is entire ions that move around to conduct electricity, whereas in metals it's only the electrons. Metals also have good thermal conductivity, meaning that they transfer heat very well. For instance, if you put one end of a metal spoon in a pot of hot water, the other end of the spoon will soon feel hot as well, even though it's not directly touching the water. This is also a function of the sea of electrons. In a metal, as electrons heat up, they are able to efficiently conduct the heat energy through the metal lattice. My task for you today is a thinking one. I've copied a small section of P table here, which shows the melting points of some of the elements. You'll see under the name of each element is its melting point in degrees Kelvin, and what I'd like you to look at are the group one and group two metals. You'll notice that the group one metals have lower melting points than the corresponding group two metals, and the group two metals have lower melting points than the transition metals. I'd like you now to think about how metallic bonding occurs, and then link that with your knowledge of valences and propose an explanation for why this trend should exist.