Crystal Growth
Crystal growth is what happens when tiny particles in a liquid slowly stack together into a solid shape.
When you stack sugar cubes in a jar, each cube locks onto the one below it in a neat grid. Crystal growth works the same way. Tiny bits in a liquid settle into place, one by one, building a solid shape with a pattern that repeats. The liquid is the jar, and the bits are the sugar cubes snapping into their spots.
Explaining crystal growth by grade level
Think about stirring salt into warm water until no more dissolves. As the water cools, the salt comes back out. It forms small, shiny blocks you can see and touch. Those blocks are crystals growing from the water.
Projects that explore crystal growth
Crystals form when atoms or molecules join together in a repeating pattern, and they build faster when they have a surface to start on. Here, laundry bluing supplies the tiny particles that give crystals something to grow on, while table salt provides the building material. Add ammonia to speed evaporation, and within hours feathery crystals sprout across the sponges as dissolved particles lock into that repeating structure.
Temperature changes how fast particles in a liquid stack together into solid crystals. In this experiment, crystal solutions sit in three different locations including a refrigerator and near a fireplace. The crystals near the fireplace grew the largest, while the cold crystals grew the most in number.
Adding certain chemicals can change how large crystals get as particles stack together from a liquid into a solid. Here, the bowls without ammonia grow small crystals about 2.5 mm tall. The bowl with the most ammonia grows crystals over 8 mm tall that overflow the bowl.
Tiny bits in a liquid can stack into a solid when the water dries up. Here, salt water creeps along yarn and drips down. As the water goes away, the bits left behind stack into a shape that hangs like an icicle.
Hot water can hold far more dissolved particles than cool water. As the solution cools, those extra particles are left with nowhere to go — so they stack together into solid crystals. In this experiment, Borax dissolves in hot water and gets poured into a hollow eggshell. As the liquid cools, crystals form along the inside walls, turning the shell into something that looks like a miniature geode.