The Atomic Number of an element is equal to:AThe mass of the atom.BThe number of neutrons.CThe number of protons.DThe number of protons + neutrons.

Break Down the Problem

1. Identify the meaning of the atomic number.
2. Analyze each given option to determine which one accurately defines the atomic number.

Relevant Concepts

• The atomic number (Z) of an element is defined in the context of atomic structure. It represents the number of protons in the nucleus of an atom.

Analysis and Detail

1. Option A (The mass of the atom): This is incorrect. Atomic mass refers to the total number of protons and neutrons, not just protons.
2. Option B (The number of neutrons): This is also incorrect, as the atomic number does not measure neutrons.
3. Option C (The number of protons): This is correct. The atomic number is specifically defined as the number of protons in an atom.
4. Option D (The number of protons + neutrons): This definition refers to atomic mass, not the atomic number.

Verify and Summarize

Based on the analysis, the only correct definition of atomic number is found in Option C. The other options do not accurately represent the concept.

Final Answer

C. The number of protons.