What is calcium?
What’s in a calcium atom?
How did calcium get to Earth?
After the star is done changing its atoms to iron, it explodes, shooting the calcium atoms out into a new nebula. Many of the calcium atoms in our nebula got made into part of the Earth. So many calcium atoms reached Earth, in fact, that calcium is the fifth most common element in the Earth’s crust.
Calcium in rocks
Most of the calcium on Earth is mixed with carbon to make molecules of calcium carbonate. That’s what sedimentary rocks like limestone and chalk are made out of. Then we burn limestone to make cement and concrete.
Calcium in eggshells and bones
But calcium is also one of the main atoms involved in making living creatures. Sponges and other animals make their hard structure out of calcium. All chordates make their bones and eggshells out of calcium.
How do people get calcium?
Others eat tofu, beans, almonds, and kale to get enough calcium.
What if you don’t get enough calcium?
Kids who don’t get enough calcium can get rickets, where your leg bones are weak and curved.
Learn by doing – an experiment with chalk
More about limestone
And about marble
How calcium makes eggshells