Which term describes a substance made up of atoms of two or more different elements joined by chemical bonds?

Which term describes a substance made up of atoms of two or more different elements joined by chemical bonds?

• A. Compound
• B. Molecule
• C. Element
• D. Alloy

Answer: (A)

A compound is a substance formed when atoms of two or more different elements join together by chemical bonds in fixed, definite proportions. This is exactly what the description is getting at: elements combine chemically to make something new with properties different from the original elements. For example, water (H2O) combines hydrogen and oxygen in a specific ratio to form a liquid with its own characteristics. A molecule is a general term for two or more atoms bonded together, but it can be made of the same element (like O2) as well as different elements, so it’s not limited to substances with two or more elements. An element is pure—made of only one kind of atom—so it cannot be two different elements in one substance. An alloy is a mixture of elements (often metals) that is typically a physical blend rather than a single chemical compound with a fixed formula, so it doesn’t fit the description of atoms bonded into a new substance with a definite composition.

A compound is a substance formed when atoms of two or more different elements join together by chemical bonds in fixed, definite proportions. This is exactly what the description is getting at: elements combine chemically to make something new with properties different from the original elements. For example, water (H2O) combines hydrogen and oxygen in a specific ratio to form a liquid with its own characteristics.

A molecule is a general term for two or more atoms bonded together, but it can be made of the same element (like O2) as well as different elements, so it’s not limited to substances with two or more elements.

An element is pure—made of only one kind of atom—so it cannot be two different elements in one substance.

An alloy is a mixture of elements (often metals) that is typically a physical blend rather than a single chemical compound with a fixed formula, so it doesn’t fit the description of atoms bonded into a new substance with a definite composition.