Chapter 7: Chemical Composition
Date:____________
Section 1: Measuring Matter - Notes
Objectives:
 Explain how a mole is used to indirectly count the number of particles of matter.
 Relate the mole to a common everyday counting unit.
 Convert between moles and number of representative particles.
Counting Particles:

Chemists need a convenient method for accurately _____________________ the number of
atoms, molecules, or formula units of a substance.

The ______________ is the SI base unit used to measure the amount of a substance.

1 mole is the amount of atoms in 12 g of pure carbon-12, or ___________________________
representative particles
o
________________________________________________________________________

The number is called _____________________________ number.

This relationship allows us to ______________________________ by _____________________
them.

Converting Between Moles and Particles:

Moles to particles:
o

Example: How many atoms are in 3.50 mol of He?
Particles to moles:
o
Example: If there are 1.1 x 1022 Ag atoms, how many moles of Ag are there?
Practice:

Calculate the number of molecules in 11.5 mol of water.

How many moles are in 5.75 x 1024 atoms of aluminum?

How many molecules of AgNO3 are there in 3.25 mol of AgNO3? How many atoms are there?