The Scientific Name: Calcium (Ca)
At its core, calcium is a chemical element with the symbol 'Ca' and atomic number 20. In the scientific world, particularly chemistry, this is its name. It belongs to Group 2 of the periodic table, making it an alkaline-earth metal. The name 'calcium' originates from the Latin word calx, a term historically used for limestone and lime. This provides a direct link between the element and its compounds, which have long been known and utilized by humans.
Pure, elemental calcium was first isolated in 1808 by Sir Humphry Davy using electrolysis. Due to its high reactivity, it is not naturally found in its pure metallic form on Earth, but rather in a wide array of compounds. These compounds are where calcium truly earns its common "other names." While the element name never changes, the context in which calcium appears determines its more common alias.
Common Names for Calcium Compounds
Many of the substances we encounter daily, from building materials to medicines, are calcium compounds with their own specific, non-scientific names. These aliases are often what people are thinking of when they ask "what is calcium also known as?"
Calcium Oxide (CaO): Quicklime, Burnt Lime, or Lime
Calcium oxide is a white, crystalline solid known by several common names, most famously quicklime or burnt lime. It is produced by heating calcium carbonate (limestone) in a process called calcination. Quicklime is highly reactive, and its ability to vigorously react with water, releasing heat, is the origin of the term "quick" or "living" lime. It has been used for centuries to make plaster and mortar and is a key ingredient in cement.
Calcium Hydroxide (Ca(OH)₂): Slaked Lime or Hydrated Lime
When water is added to quicklime, it undergoes an exothermic reaction to form calcium hydroxide. This substance is known as slaked lime or hydrated lime. Slaked lime is used in various applications, including water treatment to reduce acidity, dental fillers, and as a component in plasters and mortars.
Calcium Carbonate (CaCO₃): Limestone, Chalk, or Marble
This is perhaps the most widely recognized group of calcium aliases. Calcium carbonate is the primary constituent of several common rocks and materials.
- Limestone: A sedimentary rock composed mainly of calcium carbonate, often formed from the fossilized remains of marine life.
- Chalk: A soft, porous form of limestone made from the microscopic shells of marine plankton.
- Marble: A metamorphic rock that forms when limestone is subjected to high heat and pressure. Calcium carbonate is also the active ingredient in many calcium supplements and antacids.
Calcium Sulfate (CaSO₄): Gypsum or Plaster of Paris
Calcium sulfate, when naturally occurring, is combined with water to form a mineral called gypsum. When gypsum is heated, it forms a hemihydrate known as Plaster of Paris, a building material famously used for medical casts and artistic applications.
The Role of Calcium in the Human Body
In the context of health and biology, calcium is understood as the body's most abundant mineral. It is not referred to by another name, but rather its function is emphasized. For instance, you hear about calcium for bone health, for muscle function, and for nerve signaling. Almost all of the body's calcium is stored in the bones and teeth, providing structure and hardness. The remaining calcium is crucial for many vital processes and is often in the form of calcium ions (Ca²⁺).
Comparison of Common Calcium Compounds
| Common Name | Chemical Formula | Description | Primary Uses |
|---|---|---|---|
| Quicklime | CaO | A white, crystalline, highly reactive solid. | Cement manufacturing, steel production, water treatment |
| Slaked Lime | Ca(OH)₂ | A white powder formed by reacting quicklime with water. | Plaster, mortar, dental fillings, agriculture |
| Limestone / Chalk | CaCO₃ | A sedimentary rock or soft, porous rock composed of marine fossils. | Construction, soil neutralizer, calcium supplements |
| Marble | CaCO₃ | A metamorphic rock formed from limestone under heat and pressure. | Statues, countertops, high-end building materials |
| Gypsum | CaSO₄·2H₂O | A mineral that naturally combines with water. | Plaster, drywall, agricultural soil conditioner |
| Plaster of Paris | CaSO₄·½H₂O | A powder made from heated gypsum. | Medical casts, art, architectural details |
Conclusion: Naming the Chemical vs. the Compound
When considering "what is calcium also known as," it is important to distinguish between the element and its compounds. The element itself is called calcium, an alkaline-earth metal whose name has roots in the Latin word for lime. However, the vast majority of its common aliases—such as quicklime, limestone, and gypsum—refer to the various compounds that calcium forms with other elements. These different names are not just casual alternatives but reflect the distinct chemical composition, properties, and applications of these ubiquitous substances, from bones to building materials.
For further reading on the chemical properties of calcium, you can consult Britannica.
