Matter, mixtures and separation

Particles, mixtures and pure substances, and more separation methods. Read one part at a time and tap “I know this”. Then test yourself in the quiz.

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Particles

Melting: the particles break free and move about.

State	How the particles are arranged	How they move
Solid	Packed tightly, in rows	Only vibrate in place
Liquid	Close together, but not in rows	Slide past each other
Gas	Far apart	Move fast in all directions

Ice floats on water, because ice is less dense.
Droplets on the outside of a glass of ice water: water vapour from the air condenses.
Salt on an icy path lowers the freezing point.

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Word	Meaning
Mixture	Two or more substances mixed without making a new substance; they can be separated again (sand and water, salt water)
Pure substance	Only one substance
Homogeneous mixture	You cannot see the parts (salt water)
Suspension	Undissolved bits in a liquid (muddy water)
Insoluble	Does not dissolve in water (sand)
Saturation point	The most that can dissolve

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Mixture	Method
Sand and water (keep the water)	Filter
Salt from salt water	Evaporate
Iron and sand	Magnet
Small stones and flour	Sieve
Two liquids that have mixed (different boiling points)	Distil
Oil and water (do not mix)	Let them settle into layers and pour the oil off the top
Cream from milk	Centrifuge (spin fast)
Small stones among dry beans	Hand-sorting
Muddy water	Let it settle and pour off the clear water (decanting)

Distillation: the steam cools and becomes water again.

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Remember this: your summary

Heat a substance: the particles move faster and spread out.
A gas can be compressed most easily; more gas in a smaller container = higher pressure.
Melting needs heat; dissolving needs a liquid.
Separate: filter, evaporate, magnet, sieve, distillation (liquids with different boiling points), centrifuge (cream from milk).
In a physical change (melting, freezing, dissolving) no new substance forms, and it can usually be reversed. A chemical change (rusting, burning) makes a new substance and is hard to reverse.

Write these points in your book. Read them again the night before the test.

Memory trick

Choose by the difference: size → sieve/filter, magnetic → magnet, boiling point → distil, weight → centrifuge.

Flash cards · Tap to turn over

First say what the word means, then turn the card over.

Test yourself · Part 2

Read the question and the answer. Is the answer right? Tap True or False.

Now the real quiz!

The quiz has many more questions on this topic. Every question shows straight away whether you are right and explains why.

For parents

Read one part together and ask your child to tell it back in their own words.
The ticks (“I know this”) are saved on this device only. We never ask for names or emails.

Follows CAPS for Grade 6 Natural Sciences and Technology. Always check your teacher’s notes and textbook too.