The material lists 207.19 as the weight for lead. This figure refers to the atom's what?

The material lists 207.19 as the weight for lead. This figure refers to the atom's what?

• A. Atomic weight
• B. Molar mass
• C. Isotopic mass
• D. Density

Answer: (A)

The number 207.19 is the atomic weight—the average mass of lead atoms in atomic mass units, taking into account the natural mix of lead isotopes. It reflects how heavy a typical lead atom is on average, not the mass of a single isotope. For comparison, the mass of a specific isotope (isotopic mass) would be about a single isotope’s value (and would differ slightly from 207.19), and the molar mass would be the same numeric value expressed in g/mol when relating to one mole of atoms. Density is a completely different property and would have a much smaller value (about 11.34 g/cm³ for lead).

The number 207.19 is the atomic weight—the average mass of lead atoms in atomic mass units, taking into account the natural mix of lead isotopes. It reflects how heavy a typical lead atom is on average, not the mass of a single isotope. For comparison, the mass of a specific isotope (isotopic mass) would be about a single isotope’s value (and would differ slightly from 207.19), and the molar mass would be the same numeric value expressed in g/mol when relating to one mole of atoms. Density is a completely different property and would have a much smaller value (about 11.34 g/cm³ for lead).