Conduction and Convection

Conduction and Convection

Conduction

Heat energy can be transferred through a substance by conduction. A good conductor of heat is metal, this is because the atoms within the metal are close together. This will help because the heat can be transferred from one to another quicker then if the molecules were spread out. On the other hand, non-metals and gases are usually poor conductors of heat, this is because non-metals have fewer free electrons. The electrons in non-metals are held tightly, they are not allowed to move freely. Once the electrons in a piece of metal have left their atoms and moved about, there are parts of the metal atoms left behind, they are called charged metal ions. The ions are crowded close together and they constantly vibrate. When the metal gets hotter, the more energy the vibrations have and when the metal gets colder, the less energy the vibrations have. This energy is called kinetic energy, it is transferred from the hot and cool parts of the metal by the free electrons. When the free electrons pass through the metal, they are slowly joining up with the ions.

Convection

Convection happens when particles with a lot of energy in a liquid or gas rearrange and take the place of the particles with less heat energy. Heat energy is moved about from hot places to cooler places by convection. When liquids and gases are heated they expand. This is because the particles in liquids and gases tend to move faster when they are heated than they do when they are cold. Therefore, the particles take up more volume. This is because the gap between the particles widens, while the actual partices stay the same size. When liquids or gases are in hot areas they are less dense than when liquids and gases are in cold areas, so it rises in small places. The denser cold liquid or gas falls into warm places. To this extent, convection currents that transfer heat from place to place are set up.