Question

question 18 (5 points) listen pb has an atomic mass of 82. if an atom of that element has an atomic mass of 80, that atom is known as a) magnetic. b) a stereoisomer. c) radioactive. d) an isotope.

Explanation:

1. Recall the definitions:

• Isotopes are atoms of the same element with the same atomic number (number of protons) but different mass numbers (sum of protons and neutrons).
• Lead (Pb) has an atomic number of 82 (given atomic mass here refers to atomic number? Wait, actually, atomic number is the number of protons, and atomic mass is the mass. Wait, correction: The atomic number of Pb is 82 (number of protons). Isotopes have the same atomic number (same element) but different mass numbers (due to different number of neutrons). So if a Pb atom has a different mass (80 vs. the typical, but actually, the atomic number is 82, so same element, different mass – that's an isotope.
• Magnetic refers to properties related to electron spin alignment, not mass.
• Stereoisomers are molecules with same formula and connectivity but different 3D arrangement, not atoms.
• Radioactive is a property of some isotopes, but the term for same element different mass is isotope. So the atom with same atomic number (82, Pb) but different mass (80) is an isotope.

Answer:

D) an isotope.