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Solid, liquid or gas?

An iceberg in Arctic waters. Here water can be seen in its solid state (ice) and liquid state (liquid water). In its third state,...Read More >>An iceberg in Arctic waters. Here water can be seen in its solid state (ice) and liquid state (liquid water). In its third state, as a gas (water vapour), it is invisible in the air. Most substances exist in one of three states: solid, liquid or gas. They change from one state to another when they are heated or cooled. Water is a liquid at room temperature, but if you freeze it, it becomes a solid (ice). When boiled it turns into a gas (water vapour or steam).



 

A hot spring at Waiotapu, New Zealand. The three states of matter are shown here: solid (rock), liquid (water) and gas (vapour...Read More >>A hot spring at Waiotapu, New Zealand. The three states of matter are shown here: solid (rock), liquid (water) and gas (vapour rising from the spring).


This diagram shows water in its three states: solid (ice), liquid (water) and gas (water vapour). It shows how the water...Read More >>This diagram shows water in its three states: solid (ice), liquid (water) and gas (water vapour). It shows how the water molecules are joined together in each state. In ice the molecules are joined in a fixed pattern. In liquid water they are quite close, but can move about. In water vapour they are spread apart.

Molecules

The molecules in a solid are tightly packed and do not move about much. This is why solids have a fixed shape. The molecules in a liquid are not all joined together. They move about more and spread out to fill the shape of their container. The molecules in a gas are far apart. They move about a lot and fill the container they are in. This is why gases have no fixed shape. 

Solids can change directly into gases. This process is called sublimation.

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