Advanced metal
The structure of metal
Metals:
- are good conductors of electricity
- are good conductors of heat
- have lustre (shine)
- are malleable (able to be beaten into a shape)
- are ductile (able to be drawn into a wire)
- are solid at room temperature, with high melting points
- have a high density
To understand why these properties are specific to metal, it is important to understand something about the structure of metal. This chapter will connect some previous knowledge, with the attributes of metal.
Atoms in metal form a regular, three-dimensional lattice pattern where the layers of atoms can glide over each other and easily move into other positions. See image 1.
From a study of the sub-atomic structure of metal, it is already known that metals tend to give away their valence electron/s, allowing the electrons to move freely in the gaps between atoms. These delocalised electrons belong to the metal lattice rather than to any specific atom. (Electrons that stay with their atoms are localised and usually sit on the inner electrons shells of an atom). These delocalised electrons are free to move around the lattice, which means metal readily transfers energy and therefore readily conducts heat and electricity.
Arranged in the lattice formation, the delocalised electrons hold the cations in place because of a negative to positive charge called electrostatic force. Metallic bonding is the electrostatic force between atoms in a metal lattice. This attraction, and the flexibility of the relationship between metal particles, explains the malleability and ductility of metal compared to non-metallic elements.
See animation 1.
Remember that the transition metals are an exception. Even though they have one or two electrons on their outer shell, their second to outermost shell is not completely full. This irregular electron configuration means that the behaviour of transition metals is harder to predict, which accounts for the variable ability of transition metals to conduct heat and electricity.
Another thing we can deduce from metal's properties is that the forces between its particles are strong, implied by its high melting point, and that metal particles come tightly packed together, indicated by its high density. It can also be assumed that metal reflects, rather than absorbs, light due to its lustre.
