Are two atoms of the same element always identical?

• A. Yes, because all atoms of an element have the same number of neutrons.
• B. No, because they can have different numbers of protons.
• C. No, because they can have different numbers of neutrons.
• D. Yes, because all atoms of an element have the same mass.

Answer: (C)

Verified step by step guidance

1. Understand the definition of an element: all atoms of an element have the same number of protons, which defines the element's identity.
2. Recognize that atoms of the same element can have different numbers of neutrons; these variants are called isotopes.
3. Recall that isotopes have the same atomic number (protons) but different mass numbers due to varying neutrons.
4. Conclude that atoms of the same element are not always identical because their neutron count can differ, affecting their mass.
5. Therefore, the correct reasoning is: No, because they can have different numbers of neutrons.