1. The Mole Concept Avogadro’s Number = 6.022 x 10 23

2. Some common collections and the numbers of items in them. Timberlake, Chemistry 7 th Edition, page 179

3. Counting Atoms  Chemistry is a quantitative science - we need a "counting unit." MOLE  The MOLE  1 mole is the amount of substance that contains as many particles (atoms or molecules) as there are in 12.0 g of C-12.

4. Amadeo Avogadro (1776 – 1856) 1 mole = 602213673600000000000000 or 6.022 x 10 23 thousands millions billionstrillions quadrillions ? There is Avogadro's number of particles in a mole of any substance. Particles in a Mole

5. Amadeo AvogadroAmadeo Avogadro (1766-1856) In 1811, he proposed that equal volumes of gas (at the same temperature and pressure) will contain the same number of particles regardless of the type of particle. He never knew his own number; it was named in his honor by a French scientist in 1909. Its value was first estimated by Josef Loschmidt, an Austrian chemistry teacher, in 1895.

6. Avogadro’s Number  A mole of any substance contains as many elementary units (atoms and molecules) as the number of atoms in 12 g of the isotope of carbon- 12.  This number is called Avogadro’s number N A = 6.02 x 10 23 particles/mol  The mass of one mole of a monatomic element is called the gram atomic mass.  Example: For helium, the mass of 1 mole of He atoms is 4.0 g.

7. 1 Mole of Particles

8. Names of Particles You will encounter several different names for particles.  The term representative particles is used for any kind of substance.  Formula unit is used for ionic compounds.  Molecule is used for covalent compounds.  Atom is used for monatomic elements. All four terms indicate particles!

9. Dimensional Analysis  Dimensional Analysis is a mathematical method for solving problems that include measurements.  The original number is multiplied by one or more conversion factors to convert from one unit to another.  This works because multiplying by a conversion factor is equivalent to multiplying by one.

10. Formula Mass and Molar Mass Formula mass Formula mass is the sum of atomic masses of all atoms in one formula unit or molecule. Molar mass Molar mass = formula mass in grams. example: NaCl has a formula mass of 58.5 a.m.u. example: NaCl has a molar mass of 58.5 grams this is composed of a unit of NaCl this is composed of a 6.02 x10 23 units of NaCl