Page 44 - The Periodic Table Book

20
Ca Calcium

Discovery: 1808
20 20 20 State: Solid
Alkaline Earth Metals shiny surface. enough to cut Crystals of pure calcium
Forms
This crystal has a
This pure
metal is soft
refined in a laboratory
with a knife.

Calcite
Large,
fang-like
crystals
These column-
shaped crystals
contain calcium
carbonate.

Aragonite
Bones are hardened
by calcium phosphate.

Snake skeleton

The most abundant metal in the human contain the compound calcium phosphate.
body, calcium is also the fifth most The hard, outer layers of many other animals,
common element on Earth. It appears in such as the shells of sea snails, are made of
many minerals: calcite and aragonite are made calcium carbonate. Calcium is very important
of a compound of calcium and carbon called in our diet. We get calcium by eating calcium-
42 calcium carbonate. Bones in animal skeletons rich food, including dairy products, green

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