There are millions of different substances in the world. Each can be identified by its properties. Properties describe a substance and how it acts. They include its appearance, what it does when heated or cooled, and how it reacts with other substances.
There are millions of different substances in the world. Each can be identified by its properties. Properties describe a substance and how it acts. They include its appearance, what it does when heated or cooled, and how it reacts with other substances.
Physical properties
It’s easy to tell whether a substance is a solid, liquid or gas simply by looking at it. What we are seeing are physical properties.
Testing a substance for its physical properties doesn’t destroy the substance, or change it into anything new.
Here are the most useful physical properties of a substance:
- whether it’s a solid, liquid or gas at room temperature (normally this is 25ËšC)
- the temperatures at which the substance freezes or boils (known as its freezing point and boiling point)
- its appearance (such as its colour and texture, the shape ofany crystals vithin it and whether it is shiny or dull)
- its density (how heavy it is compared to other substances of the same size)
- how hard or brittle the substance is (whether it is easily scratched or whether it crumbles)
- whether the substance dissolves in different liquids (known as solubility)
- its ability to let heat or electricity pass through it (known as its thermal and electrical conductivity).
Solids, liquids and gases
Substances exist in either solid, liquid or gaseous form. These forms are known as
the states (or phases) of matter.
Solids, liquids and gases have very different physical properties. Think of the van below.
The bodies of cars and vans only change shape when they are in an accident or when they are broken up to be recycled.
Solids cannot be compressed (squashed to make them smaller). Try to compress a sugar cube and it might crumble, but the volume of sugar is exactly the same as it was before. The fact that solids do not change shape or size allows them to be used to build structures.
Liquids are similar to solids in that they don’t change their size and are in-compressible (unable to be compressed or squashed). They differ from solids in that they can flow and change shape. Think of orange juice it splashes about and can be poured from one container into another, taking on a new shape.
The ability of liquids to squeeze along pipes and hoses without changing volume allows them to be used in hydraulic (powered by liquid) systems such as car brakes.
Gases are often invisible and many have no odor (smell). Water vapor is a gas that is invisible because it is colorless and its particles are spread too far apart for the gas to be seen.
Gases differ from solids and liquids in that they can be compressed. This property allows gases to be squeezed into smaller volumes such as barbecue gas cylinders. It also makes them useful in shock absorbers found in the suspension of bikes and cars.
The 4th and rarest state of matter
There is a fourth state of matter but it is very rare on Earth. Plasma is a gas-like state that only exists at temperatures above 6000ËšC, making it common on stars but not here.
Plasma ball video
https://www.youtube.com/watch?v=XEl5woSQgiM
Plasma is the most common state of matter in the universe