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Elements for Kids

Calcium

The element calcium

  • Symbol: Ca
  • Atomic Number: 20
  • Atomic Weight: 40.078
  • Classification: Alkaline earth metal
  • Phase at Room Temperature: Solid
  • Density: 1.55 grams per cm cubed
  • Melting Point: 842°C, 1548°F
  • Boiling Point: 1484°C, 2703°F
  • Discovered by: Sir Humphry Davy in 1808


Calcium is the third element in the second column of the periodic table. It is classified as an alkaline earth metal. Calcium atoms have 20 electrons and 20 protons. There are 2 valence electrons in the outer shell. Calcium is an important element for life on Earth and is the fifth most abundant element in the Earth's crust.

Characteristics and Properties

Under standard conditions calcium is a shiny, silvery metal. It is fairly soft and is the lightest of the alkaline earth metals due to its low density. Although it is a bright silver when first cut, it will quickly form a gray-white oxide on its surface when exposed to air.

When exposed to water, calcium will react and generate hydrogen. When burned, it produces a bright orange-red flame.

Where is calcium found on Earth?

Calcium is rarely found in its elemental form, but is readily found throughout the Earth mostly in the form of rocks and minerals such as limestone (calcium carbonate), dolomite (calcium magnesium carbonate), and gypsum (calcium sulfate). It is the fifth most common element in the Earth's crust.

Calcium carbonate is one of the major components of many rocks and minerals including limestone, marble, calcite, and chalk.

Calcium is also found in ocean water and is about the eighth most abundant element found in the ocean.

How is calcium used today?

Calcium in its elemental form has few industrial uses, but its compounds with other elements are widely used.

One important compound is calcium oxide (CaO), which is also called lime. Lime is used in a number of applications including the production of metals, removing pollution, and water purification. It is also used to produce additional chemicals.

Calcium compounds, rocks, and minerals such as limestone and marble are also used in construction. Gypsum is used to make plaster of Paris and drywall. Other applications include antacids, toothpaste, and fertilizer.

Calcium is also a very important element in both plant and animal life. In the human body calcium is part of a compound called hydroxyapatite which is what makes our bones and teeth hard. Calcium is the fifth most abundant element in the human body, making up around 1.4% of the body's mass.

How was it discovered?

The first scientist to discover and isolate the element calcium was English chemist Sir Humphry Davy in 1808.

Where did calcium get its name?

Sir Humphry Davy named calcium after the Latin word "calx" which is what the Romans called lime.

Isotopes

Calcium has four stable isotopes including 40Ca, 42Ca, 43Ca, and 44Ca. Two more calcium isotopes (46Ca and 48Ca) have very long half-lives and are considered mostly stable. Around 97% of naturally occurring calcium is in the form of the isotope 40Ca.

Interesting Facts about Calcium

More on the Elements and the Periodic Table

Elements
Periodic Table

Alkali Metals
Lithium
Sodium
Potassium

Alkaline Earth Metals
Beryllium
Magnesium
Calcium
Radium

Transition Metals
Scandium
Titanium
Vanadium
Chromium
Manganese
Iron
Cobalt
Nickel
Copper
Zinc
Silver
Platinum
Gold
Mercury
 Post-transition Metals
Aluminum
Gallium
Tin
Lead

Metalloids
Boron
Silicon
Germanium
Arsenic

Nonmetals
Hydrogen
Carbon
Nitrogen
Oxygen
Phosphorus
Sulfur
 Halogens
Fluorine
Chlorine
Iodine

Noble Gases
Helium
Neon
Argon

Lanthanides and Actinides
Uranium
Plutonium

More Chemistry Subjects

Matter
Atom
Molecules
Isotopes
Solids, Liquids, Gases
Melting and Boiling
Chemical Bonding
Chemical Reactions
Radioactivity and Radiation
 Mixtures and Compounds
Naming Compounds
Mixtures
Separating Mixtures
Solutions
Acids and Bases
Crystals
Metals
Salts and Soaps
Water
 Other
Glossary and Terms
Chemistry Lab Equipment
Organic Chemistry
Famous Chemists


Science >> Chemistry for Kids >> Periodic Table


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