Chapter 2 - Sections 2.1-2.9 - Exercises - Problems by Topic - Page 82: 87a

$1.01\times10^{23}\ atoms\ P$

1. Use the molar mass of phosphorus and Avogadro's number as conversion factors in order to determine the number of atoms of phosphorus. 2. $5.18 g\ P \times\frac{1\ mol\ P}{30.98\ g\ P}\times\frac{6.022\times10^{23}}{1\ mol\ P}= 1.01\times10^{23}\ atoms\ P $