Question

The element lead (pb) consists of four naturally occurring isotopes with atomic masses 203.97302, 205.97444, 206.97587, and 207.97663. the relative abundances of these four isotopes are 1.4, 24.1, 22.1, and 52.4%, respectively. what is the atomic mass of pb?

Answer 1

Formula for calculating [Average Atomic Mass] of Pb (Lead):AAM of [element] = (Mass of isotope) * (Relative abundance) and you can repeat the "(Mass of isotope) * (Relative abundance)" part for each isotope! Therefore...AAM of Pb=(203.97302)(0.014)+(205.97444)(0.241)+(206.97587)(0.221)+(207.97663)(0.524)AAM of Pb = 207.21688371 amu [OR] 207.2 amu on most periodic tables.