Which of the following best describes how elements and compounds are identified?

• A. Elements are identified by their chemical formulas, while compounds are identified by their atomic number.
• B. Elements and compounds are both identified solely by their physical state at room temperature.
• C. Elements are identified by their atomic number, while compounds are identified by their chemical formulas.
• D. Elements are identified by their mass number, while compounds are identified by their melting point.

Answer: (C)

Verified step by step guidance

1. Understand that elements are pure substances consisting of only one type of atom, and each element is uniquely identified by its atomic number, which is the number of protons in its nucleus.
2. Recognize that compounds are substances formed when two or more different elements chemically combine in fixed ratios, and they are represented by chemical formulas that show the types and numbers of atoms involved.
3. Recall that the atomic number is a fundamental property of an element and does not change, making it the definitive identifier for elements.
4. Note that chemical formulas provide detailed information about the composition of compounds, indicating which elements are present and in what proportions.
5. Conclude that the best description is: Elements are identified by their atomic number, while compounds are identified by their chemical formulas.