Metals

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EXPLAINING THE PROPERTIES OF METALS

Density

Metals have high densities. This is due to the fact that the atoms within a metal are tightly packed together. When a layer of atoms is placed on top of another layer, the atoms move into the gaps between the atoms of the previous layer.

Metals have various densities due to their different atomic masses and how tightly packed these atoms are.

NOTE how an atom in the middle of the arrangement touches six other atoms

The tightly packed arrangement of metal atoms.

Electrical Conductivity

Metals are good conductors of electricity. The valence shell electrons in a metal are free to move within the metal structure. This means when electrons flow out of the negative terminal of a power supply and into a metal, electrons within the metal are able to carry the current to the positive terminal of the power supply. The electrons will be jumping from atom to atom.

Flow of electrons through a metal.

Electrons from the negative terminal power supply

Electrons going to the positive terminal of a power supply

Melting and Boiling Points

Metals have high melting and boiling points. This suggests that there are strong forces of attraction between the atoms in a metal. These strong forces are a result of the free-moving valence electrons. Because these electrons are free moving, a metal actually consists of positive ions (the nuclei) surrounded by a negative 'sea of electrons'. The 'sea' of electrons are attached to neighbouring positive ions. These attractive forces require a lot of energy to break.

Malleabilitiy and Ductility

As previously explained, the attractive forces between metal atoms is strong. However, they are not rigid (fixed in one place). This means layers of atoms can slide over each other when force is applied to them. When the force is removed the atom's closely packed arrangement is restored.

Atoms slide past each other and settle in a new position once the force is removed.

Thermal Conductivity

1) Particles inside a metal vibrate in a fixed position. When the heating process begins, the particles closest to the heat source gain kinetic energy and vibrate more vigorously. These more energetic particles collide with unheated particles, passing some of the kinetic energy on and also causing those particles to start vibrating more vigorously.

2) The process of particles colliding continues along the metal rod. In this way the heat energy is transferred from the hot end of the rod, to the cold end, until the entire rod is hot.

Explaining The Properties of Metals