The Three States of Matter
The three states, SOLID, LIQUID and GAS are called the three states of matter (see Kinetic Theory)
The boiling point of a substance is the temperature that causes it to change from a liquid to a gas
At a temperature ABOVE its boiling point a substance will always be a gas
The melting point of a substance is the temperature that causes it to change from a solid to a liquid
At a temperature below its melting point a substance will always be a solid
At a temperature between its melting point and boiling point it will be a liquid
|Substance||Melting point||Boiling point||State at room temperature|
|Water||0° C||100° C||Liquid|
|Mercury||-39 C||357 C||Liquid|
You don’t need to remember the melting points and boiling points but you DO need to know why each substance is a solid, liquid or gas.
You DO need to know the melting point and boiling point of water
Boiling point of water = 100° C
Melting point of water = 0° C
A substance can be made to change state by making it hotter or colder
MELT : When a solid turns to a liquid. This happen as soon as the substance reaches (or goes above) a temperature called its melting point
eg WAX melts when heated.
EVAPORATE: When a liquid turns to a vapour
BOIL: This is when a liquid turns to a vapour at its boiling point.
eg WATER boils when heated.
SUBLIME This is when a solid turns to a vapour without becoming a liquid
eg IODINE turns from a solid to a purple vapour when heated
FREEZE (or solidifying): This is when a liquid turns to a solid. This happens when the liquid cools to below its melting point.
SUBLIME This is when a vapour turns to a solid without becoming a liquid
eg IODINE turns from a purple vapour to a black solid when heated
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