Calcium occurs widely in compounds with very different roles. Calcium phosphate helps build bone, while calcium carbonate forms limestone. Heating limestone releases carbon dioxide and leaves calcium oxide, connecting geological materials to industrial processing and showing how a reaction changes the substances present.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
How does a lime binder harden?
Calcium compounds in lime and cement
FOLLOW THIS RELATIONSHIP
Transform mineral material
Limestone supplies calcium carbonate that industrial processing can convert into lime-related binder ingredients, changing chemical form while retaining calcium within the material system.
Explore the model (optional)
CaFORM → INTERACTION → CONSEQUENCE
Follow the explanation in either direction. These are authored steps, not a physical clock.
Atomic identity, reference properties and structure models
INTERACTIVE 3D20 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Ar] 4s2. Grouping electrons by principal shell connects the neutral-atom configuration to periodic-table patterns.
What this representation means
A three-dimensional counting diagram. Dots are count markers, not measured electron positions; spherical placement and spacing are arbitrary. There are no electron trajectories here. Orbitals describe quantum states.
Lime had served building traditions for centuries, yet its metallic constituent was unknown. Chemists recognized lime as a compound whose element resisted isolation. Davy obtained calcium in 1808 through electrochemical work involving a mercury amalgam. The result distinguished a reactive metal from the familiar limestone and lime compounds that had already shaped a long history of human construction.
Before 1808
Lime used in construction
Heating and processing calcium-bearing stone supplied materials for mortar and plaster.
1808
Calcium isolated
Davy's electrochemical work produced calcium and established the metal behind lime.
Calcium occurs in such as limestone, gypsum, fluorite, and apatite, and in biological structures including bones and shells. These materials place calcium in different compounds. chemistry also links it to caves and hard water, where dissolved substances can move and later deposit as new mineral material.
Calcium is a reactive alkaline-earth metal that combines with oxygen and reacts with water. Its compounds display a much wider range of familiar behavior. Calcium carbonate, for example, participates in dissolution and processes influenced by carbon dioxide, connecting chemical reactions with limestone landscapes and mineral deposits.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
CITE THIS PAGE
Family labels and the group-3 layout are teaching conventions. A table position does not establish an unknown bulk property. Electronic configurations refer to neutral atoms; ions and material environments require their own account.
Read each reference property together with its units, conditions and the reference information below.
Not yet recorded: electron affinity, second ionization energy, ground-state term symbol, van der waals radius, thermal conductivity, specific heat capacity, electrical resistivity, crystal structure, lattice parameter a, space group, abundance in seawater, abundance in the universe, annual production, supply-risk listing, hazard classification, biological role, cas registry number, pubchem cid, wikidata item. These families are declared and awaiting an ingestion run against the source each names; they are listed here rather than shown as empty rows.
Physical
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Phase at 20 °C
solid
293.15 K, 101.325 kPa
Melting point in K
1115 K
at standard pressure unless noted
Boiling point in K
1757 K
101.325 kPa
Density in g/cm³
1.55 g/cm³
solids and liquids at 293 K; gases at 273 K and 101.325 kPa
Atomic and electronic
Intended reference: Pauling electronegativity scale · Widely tabulated; original in The Nature of the Chemical Bond
Electronegativity in Pauling
1 Pauling
Pauling scale
First ionization energy in kJ/mol
589.8 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
176 pm
single-bond covalent radius
Common oxidation states
+2
states met in ordinary compounds; not exhaustive
Occurrence and identity
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Abundance in the crust in mg/kg
41500 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1808 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 4
Ca 1 Pauling · Calcium
Electronegativity across period 4. Exact values.
K
0.82
Ca
1
Sc
1.36
Ti
1.54
V
1.63
Cr
1.66
Mn
1.55
Fe
1.83
Co
1.88
Ni
1.91
Cu
1.9
Zn
1.65
Ga
1.81
Ge
2.01
As
2.18
Se
2.55
Br
2.96
Kr
3
Electronegativity down group 2
Ca 1 Pauling · Calcium
Electronegativity down group 2. Exact values.
Be
1.57
Mg
1.31
Ca
1
Sr
0.95
Ba
0.89
Ra
0.9
The trend uses the same reference-property values as the periodic table. Elements with no recorded value are left out of the line rather than drawn at zero.
