How do isotopes of an element differ from each other?

• A. They have different numbers of neutrons.
• B. They have different numbers of protons.
• C. They belong to different elements.
• D. They have different chemical symbols.

Answer: (A)

Verified step by step guidance

1. Recall that isotopes are variants of the same element, meaning they have the same number of protons but differ in another subatomic particle.
2. Understand that the number of protons defines the element itself, so isotopes cannot differ in proton number without being different elements.
3. Recognize that isotopes differ in the number of neutrons, which affects the atomic mass but not the chemical properties significantly.
4. Note that isotopes share the same chemical symbol because they are the same element, just with different neutron counts.
5. Conclude that the key difference between isotopes is the number of neutrons in their nuclei.