Quick answerCalcium (Ca) is an alkaline earth metal with atomic number 20 and an atomic mass of 40.078 (2023), in group 2, period 4. It was discovered by Humphry Davy in 1808. It is used for cement and concrete and dietary supplements. Its electron configuration is [Ar] 4s2.
Calcium builds bones, teeth, seashells, and limestone cliffs, it is the most abundant mineral in your body. Chalk, marble, and cement are all calcium compounds, and farmers spread lime to sweeten acidic soil. Without calcium, your muscles could not contract and your blood could not clot.
Key facts
| Symbol | Ca |
|---|---|
| Atomic number | 20 |
| Atomic mass | 40.078 (IUPAC standard atomic weight, 2023) |
| Category | alkaline earth metal |
| Group | 2 |
| Period | 4 |
| Block | s-block |
| Electron configuration | [Ar] 4s2 |
| Discovered | Humphry Davy, 1808 |
| Uses | cement and concrete, dietary supplements, steel refining, limestone for building, soil treatment |
Overview
Calcium builds bones, teeth, seashells and limestone cliffs: it is the most abundant mineral in your body and one of the most abundant elements in Earth's crust. It has atomic number 20, an atomic mass of 40.078, and the electron configuration [Ar] 4s2, and it sits in group 2, the alkaline earth metals, in period 4. Humphry Davy isolated it in 1808 by electrolysis, and named it from the Latin word for lime. Calcium never occurs as a free metal in nature; it is found in limestone, chalk, marble and gypsum, and dissolved in seawater, from which shellfish and corals build their shells and reefs. Your body stores almost all its calcium in bones and teeth, and uses the rest to contract muscles, clot blood and send nerve signals. Industry uses calcium compounds on a vast scale: limestone is burned to make cement and concrete, the backbone of construction, and farmers spread lime to sweeten acidic soil. Calcium also refines steel, treats water, and goes into dietary supplements, antacids and white paint.
Frequently asked questions
What is calcium used for?
Calcium is mainly used in cement and concrete, made from limestone, and in building stone, chalk and marble. It refines steel, treats soil and water, and goes into dietary supplements and antacids. In the body it builds bones and teeth, contracts muscles, clots blood and sends nerve signals, so it is the most abundant mineral you carry.
What is the symbol for calcium?
The chemical symbol for calcium is Ca, from its name, which comes from the Latin word calx, meaning lime. It has atomic number 20 and a standard atomic mass of 40.078, and it sits in group 2 and period 4. Humphry Davy isolated it in 1808, and it is the most abundant mineral in the human body.
What is the atomic number of calcium?
Calcium has atomic number 20, so it is the twentieth element in the periodic table. Its atom holds twenty protons and twenty electrons, and its standard atomic mass is 40.078. It is an alkaline earth metal in group 2 and period 4, with the electron configuration [Ar] 4s2, two electrons in its outer shell.
Is calcium a metal?
Yes, calcium is a metal, an alkaline earth metal in group 2 of the periodic table. It is silvery-white and fairly soft, and it reacts with water and tarnishes quickly in air. It never occurs as a free metal in nature, but only in compounds such as limestone, chalk, marble and gypsum, and in bones and shells.
Why is calcium important for bones?
Calcium is essential for bones because almost all the calcium in your body is stored there as calcium phosphate, which gives bones their strength and hardness. Children need it to grow, and adults need it to keep bones dense, since bone is constantly rebuilt. Milk, cheese, yoghurt and leafy greens are rich sources of calcium.
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Keep exploring
- Periodic table — all 118 elements
- Beryllium (Be) — another alkaline earth metal, atomic number 4
- Magnesium (Mg) — another alkaline earth metal, atomic number 12
- Strontium (Sr) — another alkaline earth metal, atomic number 38
- Barium (Ba) — another alkaline earth metal, atomic number 56
- Radium (Ra) — another alkaline earth metal, atomic number 88
Sources & last updated
- CIAAW — Standard Atomic Weights
- PubChem Periodic Table
- Wikipedia — Timeline of chemical element discoveries
Last updated: . Figures are shown with their year; where sources disagree, the value is left out rather than estimated.