A Chemist’s “Dozen”

 The particles that make up matter (ions, atoms, and molecules) are extremely small  Only large amounts of these particles can be weighed. In order to simplify these large numbers we use the mole  1Mole = x particles ▪ Particles can be atoms, molecules, ion, bananas, lollipops, etc.

 1Mole = x particles  Particles can be atoms, molecules, ion, bananas  x is known as Avogadro’s Number Amedeo Avagadro

 How does the mole get this specific value?  The value of the mole is equal to the number of atoms in exactly 12 grams of pure carbon-12. ▪ 12g C = 1 mole C atoms = x C atoms  This definition gives a relationship between mass (grams) and the number of atoms (Avagadro’s number)

 A Road Map Grams Atoms Mole Gram formula mass Molar Mass x Avagadro’s Number Remember: The Molar Mass is the sum of the weights of each element in the compound. NH 3 would be 1(14)+3(1)= 17 g/mol

 E.g. How many atoms are in one mole of pennies? 1 mole pennies x pennies = x pennies 1 mole pennies Avagadro’s Number

 E.g. How many grams are in 1 mole of sodium? 1 mol Na 23 g Na = 23 grams sodium 1 mol Na This is the Gram Formula Mass (gfm) ratio

 E.g. How many molecules are in 13 grams of H 2 SO 4 ?  Solve in two steps. 13 g H 2 SO 4 1 mol H 2 SO x molecules H 2 SO 4 = 98 g H 2 SO 4 1 mol H 2 SO 4 = x molecules H 2 SO 4 Gfm Avagadro’s Number

 E.g. How many moles are in 31 atoms of copper? 31 atoms 1 mol = x moles copper x Avagadro’s Number