Atomic Structure and Compound Properties

Steps:

• Recall that elements are defined by their atomic number, which is the number of protons in the nucleus.
• Understand that all atoms of the same element have identical atomic numbers, ensuring the same proton count.
• Evaluate each option against basic chemistry definitions: ionic vs. covalent compounds, electrical conductivity, and mixtures vs. compounds.
• Identify the statement that aligns with the definition of an element.

Why C is correct:

• By definition, the atomic number of an element equals the number of protons in its nucleus, so all atoms of that element share this fixed number.

Why the others are wrong:

• A: Many compounds are covalent (e.g., water), not ionic.
• B: Covalent compounds like sugar do not conduct electricity when molten.
• D: Mixtures have variable proportions, unlike fixed-ratio compounds.

Final answer: C