Plasma

plasma - the fourth state of matter, when learning about properties of matter.

When ice is sufficiently heated, it melts to form water. It has therefore undergone a change of state – from a solid to a liquid. Recall that in a solid, all of the particles are closely packed in a fixed position, and therefore has a fixed shape and volume. The particles in a liquid are still touching one another and are able to move around one another, therefore, a liquid still has a fixed volume but takes the shape of their container. Water evaporates from a liquid to a gas. The particles in a gas are further away from one another and take the shape and volume of their container. For certain substances, if we continue to apply heat to their gaseous form, another change of state could occur. These substances can go from a gas to a state of matter called plasma. For this change of state to occur, very strong heat must be applied. When heat is sufficiently strong, the electrons are stripped from their respective atoms, creating free electrons and positive ions. Although there are both negative and positive particles, overall, plasma is neutral as there are equal amounts of oppositely charged particles. Because there are free electrons, substances in a plasma form can conduct electricity. This is what separates a gas from plasma – gases cannot conduct electricity, but plasma can. Naturally occurring plasma include lightning and the Northern lights. Stars also exist in plasma form – in fact stars are just really hot balls of plasma. Plasma can be found in fluorescent light bulbs and neon signs. When an electrical current is passed through the mercury vapour in fluorescent light bulbs and certain noble gases in neon signs, it heats up the gases sufficiently to strip the electrons and create plasma. The technology actually goes even further beyond light bulbs and neon signs. Plasma screen TVs are made possible due to this state of matter. A plasma screen is made of many thousands of tiny dots called pixels, which are made of three fluorescent light electrodes, emitting the colours red, green, and blue. The combination of these colours can give any possible colour, which is why we can see all colours on these screens. The higher the number of pixels, the higher the definition, and the images will appear “sharper” and more detailed.