How does one isotope of a particular element differ from another isotope of the same element?

• A. They have different numbers of neutrons in the nucleus.
• B. They have different numbers of protons in the nucleus.
• C. They have different numbers of electrons in the outer shell.
• D. They belong to different elements on the periodic table.

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 and its position on the periodic table, so isotopes cannot differ in proton number.
3. Recognize that electrons can vary in number due to ionization, but this does not define isotopes; isotopes focus on the nucleus composition.
4. Identify that isotopes differ in the number of neutrons in the nucleus, which changes the atomic mass but not the chemical identity.
5. Conclude that the key difference between isotopes of the same element is the number of neutrons in their nuclei.