Crystals can grow from a solution — Chemistry, 4–6 years
When a dissolved substance gathers again, its particles can make a neat, repeating shape. Chemistry, 4–6 years.
Orderly little shapes
A crystal is a solid whose tiny particles line up in a repeating pattern. That pattern can make flat faces, straight edges or sparkling shapes, even though the particles are too small to see.
Why crystals form
A dissolved solid is spread through water, so its particles cannot make a solid shape together. When some water leaves, the particles come closer and may line up; this makes crystals instead of a loose pile.
Growing salt crystals
1. Stir salt into warm water until no more will dissolve. 2. Pour it into a shallow dish. 3. Leave it somewhere safe for several days. 4. As water leaves, salt particles join in an orderly pattern, and small crystals appear.
The salt has not vanished
It is reasonable to think the salt has gone when the water looks clear, because our eyes cannot see the separated particles. The salt is still there in the water; later, when water leaves, it can become visible again as crystals.
Salt, sugar and stones
Crystals are useful and common: salt crystals season food, sugar crystals sweeten it, and some rocks grow as crystals deep underground. Their neat shapes are clues about how their tiny particles are arranged.
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