Final answer:
The formula for calcium oxide is CaO, which stands for one calcium atom bonded to one oxygen atom. This compound is highly reactive and forms calcium hydroxide when combined with water, leading to its extensive use in industrial applications.
Step-by-step explanation:
The formula for calcium oxide is CaO. This compound is composed of one calcium atom (Ca) and one oxygen atom (O), making the ratio of calcium to oxygen 1:1 in molecular terms. In historical contexts, pure calcium oxide was used in theaters for stage lighting before the advent of electricity, and when heated to a high temperature, it emitted an intense white light. This use is the origin of the term "in the limelight".
Calcium oxide, also known as quicklime or just lime in the industrial market, is highly reactive, and its many applications leverage this reactivity. When calcium oxide is mixed with water, it forms calcium hydroxide (Ca(OH)2), which is commonly known as slaked lime, hydrated lime, or builders' lime. This reaction is fundamental in various chemical processes and in the preparation of materials like cement and plaster.