One type of atom.

One type of atom.

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

Answer: (B)

An element is a pure substance made of only one kind of atom. In an element, every atom is the same type (same number of protons), so the substance cannot be broken into simpler substances by chemical means. A compound, by contrast, contains two or more different elements chemically bonded together. A mixture is a physical blend of substances not bonded, and a molecule is a bonded group of atoms, which can be made of the same element or different elements. Saying “one type of atom” points to an element because that uniformity of atom type is the defining feature of elements.

An element is a pure substance made of only one kind of atom. In an element, every atom is the same type (same number of protons), so the substance cannot be broken into simpler substances by chemical means. A compound, by contrast, contains two or more different elements chemically bonded together. A mixture is a physical blend of substances not bonded, and a molecule is a bonded group of atoms, which can be made of the same element or different elements. Saying “one type of atom” points to an element because that uniformity of atom type is the defining feature of elements.