A mole is like a dozen. It is a name for a specific number of things. There are 12 things in a dozen, and 602 hexillion things in a mole. We'll talk about what moles are and why they are important. We will see how to abbreviate the mole number (Avogadro's number) using scientific notation, and we'll see how giant this number is.

How many atoms in 5.5 moles? How many moles is 4.6 x 10^24 sulfur atoms? We'll solve problems like these, where we convert back and forth between moles and the number of atoms or molecules that we have. We'll be using both a common sense approach, and also a standard conversion factor method. We'll learn how to use a scientific calculation to do this math, and we'll see how to round our answers with scientific notation and significant figures.

This chemistry video tutorial explains how to find the percent composition by mass of each element in a compound using a simple formula. You need to find the molar mass of the entire compound in order to calculate the mass percent of each element. This video contains plenty of examples and practice problems.