Final answer:
A compound is formed when atoms of different elements chemically react with each other. Compounds have a fixed whole-number ratio of atoms and are chemically bonded, distinguishing them from mixtures. During reactions, atoms can gain or lose electrons to form ions, but their nuclear structure remains constant.
Step-by-step explanation:
When atoms of one type react with atoms of other types, a compound is formed. This occurs when two or more elements chemically combine in a fixed whole-number ratio, resulting in the formation of new substances with unique properties. For instance, hydrogen and oxygen can react to form water (H2O), which is a compound composed of two hydrogen atoms and one oxygen atom. In the reaction, atoms are neither created nor destroyed, and can separate and recombine to form new substances, such as when water electrolyzes into hydrogen and oxygen gases.
It is important to note that compounds are different from mixtures. While compounds have atoms that are chemically bonded together, mixtures, like Gatorade, are composed of several compounds or elements mixed together without chemical bonds. During compound formation, atoms might gain or lose electrons and become ions, but they always maintain their nuclear structure, meaning the identity of the element remains unchanged.