What does it mean if the atomic mass of an element is 10.8?

• A. The element has isotopes, and 10.8 is the weighted average of their masses based on natural abundance.
• B. The element contains 10.8 neutrons in its nucleus.
• C. The atomic number of the element is 10.8.
• D. All atoms of the element have exactly 10.8 protons.

Answer: (A)

Verified step by step guidance

1. Understand that the atomic mass of an element is not usually a whole number because it represents the weighted average of the masses of all naturally occurring isotopes of that element.
2. Recall that isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different mass numbers.
3. Recognize that the atomic mass takes into account both the mass and the relative abundance of each isotope in nature, which is why it can be a decimal value like 10.8.
4. Note that the atomic number (number of protons) is always a whole number and cannot be a decimal like 10.8, so the atomic mass does not represent the number of protons.
5. Conclude that the atomic mass of 10.8 means the element has multiple isotopes, and 10.8 is the weighted average mass of these isotopes based on their natural abundance.