Topic: Counting Atoms and Formula Mass (the MOLE)

Topic: Counting Atoms and Formula Mass (the MOLE)

Lets starting my counting atoms in a single molecule • NaCl • H2SO4 • Cu(NO3)2 Na = 1 Cl = 1 total atoms = 2 H = 2 S = 1 O = 4 total atoms = 7 Cu = 1 N = 2 O = 6 total atoms = 9 What happens if there is a coefficient in the front? • 5NaCl • 3H2SO4 • 2Cu(NO3)2 Na = 5 Cl = 5 total atoms = 10 H = 6 S = 3 O = 12 total atoms = 21 Cu = 2 N = 4 O = 12 total atoms = 18

We can count the number of atoms in one molecule of water (H20). 2 H1 OBut in a 100 ml of water, how many H atoms / O atoms are there?Thousands, Millions, Billions? THINK BIGGER MUCH BIGGER MOLE VIDEO LINK

Thanks to Avogadro, we can calculate that there are … • 6680000000000000000000000 (6.68 x 1024) Hydrogen atoms in 100 ml (less then a ½ cup) of water

1 Mole = 6.02 1023 particles = Avogadro's # • Used to “count” numbers of atoms • Defined as # of atoms in 12 g or C-12 • This is the standard • So, 12 g of C-12 has ____________ atoms • This is a really big number – It’s so big because atoms are really small! • HOW SMALL?!(link) 6.02 x 1023 No, not this kind of mole!

One mole of water = 6.02 X 1023 water molecules • One mole of gorillas = 6.02 X 1023 gorillas • One mole of He atoms = 6.02 X 1023 He atoms • One mole of anything = 6.02 X 1023 of that thing

0.5 mole of C-12 = 6.0 grams of C-12 = 3.01 X 1023 atoms of C-12 Equalities • 1 mole of C-12 = • 12.0 grams of C-12 = • 6.02 X 1023 atoms of C-12

Formula mass for any element: • Formula mass of any element: • take atomic mass and replace a.m.u. with grams • 1 mole Ne = 20.179 g = 6.02 X 1023 atoms • Molar mass = formula mass over mol (g/mol) • 20.179 g/mol • Chemists use this to convert been the number of atoms to an actual mass that they can measure in the lab

Calculating Formula Mass • COUNT Atoms • LOOK UP Atomic Mass (rounded) • Multiply and Add • CH2Cl2 • C = 1 • H = 2 • Cl = 2 X 12 = 12 X 1 = 2 X 35 = 70 84 g Molar Mass = 84 g/mol

Topic: Counting Atoms and Formula Mass (the MOLE)