Element 20
Calcium
Alkaline earth
Calcium (Ca) is in the s-block of the periodic table — group 2, period 4.
Calcium is a chemical element with symbol Ca and atomic number 20.
Key data
- Atomic number
- 20
- Atomic mass
- 40.078 u
- Group / Period
- 2 / 4
- Block
- s-block
- Phase at STP
- Solid
- Density
- 1.55 g/cm³
- Melting point
- 841.9 °C
- Boiling point
- 1483.8 °C
- Electron configuration
- [Ar] 4s2
Periodic table block
Calcium is in the s-block (group 2, period 4). Elements land in the s-block when their highest-energy electrons fill an s subshell — this includes hydrogen, helium, and the reactive metals on the far left of the table.
New to this? Periodic table blocks explained: s, p, d, and f
Common uses
- •Bones and teeth
- •Cement
- •Limestone
Discovery
Year: 1808
Discovered by: Humphry Davy
Frequently asked questions
What is the atomic number of Calcium?
Calcium has atomic number 20. Its symbol is Ca and its atomic mass is 40.078 u.
What category of element is Calcium?
Calcium is classified as alkaline earth. It sits in group 2, period 4 of the periodic table.
What block of the periodic table is Calcium in?
Calcium is in the s-block (group 2, period 4). Its highest-energy electrons occupy the s subshell — you can see this in its electron configuration, [Ar] 4s2.
What is Calcium used for?
Common uses of Calcium include: Bones and teeth, Cement, Limestone.
When was Calcium discovered?
Calcium was discovered in 1808 by Humphry Davy.
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