Question

which is the weighted average mass of all naturally occurring isotopes of an element, measured in atomic mass units (amu), according to the natural abundances?

mass number

average atomic mass

atomic number

need help? review these concept resources.

read about the concept

Explanation:

• Mass number is the sum of protons and neutrons in an atom's nucleus, not a weighted average of isotopes.
• Average atomic mass is defined as the weighted average mass of all naturally occurring isotopes of an element, considering their natural abundances and measured in atomic mass units (amu).
• Atomic number is the number of protons in an atom's nucleus, unrelated to the mass of isotopes.

Answer:

B. average atomic mass