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By definition: 1 atom 12 C “weighs” 12 amu

Micro World atoms & molecules. Macro World grams. Atomic mass is the mass of an atom in atomic mass units (amu). By definition: 1 atom 12 C “weighs” 12 amu. On this scale 1 H = 1.008 amu 16 O = 16.00 amu. The average atomic mass is the weighted

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By definition: 1 atom 12 C “weighs” 12 amu

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  1. Micro World atoms & molecules Macro World grams Atomic mass is the mass of an atom in atomic mass units (amu) By definition: 1 atom 12C “weighs” 12 amu On this scale 1H = 1.008 amu 16O = 16.00 amu

  2. The average atomic mass is the weighted average of all of the naturally occurring isotopes of the element.

  3. 7.42 x 6.015 + 92.58 x 7.016 100 Naturally occurring lithium is: 7.42% 6Li (6.015 amu) 92.58% 7Li (7.016 amu) Average atomic mass of lithium: = 6.941 amu

  4. Average atomic mass (6.941)

  5. Dozen = 12 Pair = 2 The Mole (mol): A unit to count numbers of particles The mole (mol) is the amount of a substance that contains as many elementary entities as there are atoms in exactly 12.00 grams of 12C 1 mol = NA = 6.0221367 x 1023 Avogadro’s number (NA)

  6. eggs shoes Molar mass is the mass of 1 mole of in grams marbles atoms 1 mole 12C atoms = 6.022 x 1023 atoms = 12.00 g 1 12C atom = 12.00 amu 1 mole 12C atoms = 12.00 g 12C 1 mole lithium atoms = 6.941 g of Li For any element atomic mass (amu) = molar mass (grams)

  7. One Mole of: S C Hg Cu Fe

  8. 1 12C atom 12.00 g 1.66 x 10-24 g = 12.00 amu 6.022 x 102312C atoms 1 amu = molar mass in g/mol M x 1 amu = 1.66 x 10-24 g or 1 g = 6.022 x 1023 amu NA= Avogadro’s number

  9. 1 mol K 6.022 x 1023 atoms K x x = 1 mol K 39.10 g K How many atoms are in 0.551 g of potassium (K) ? 1 mol K = 39.10 g K 1 mol K = 6.022 x 1023 atoms K 0.551 g K 8.49 x 1021 atoms K

  10. 1S 32.07 amu 2O + 2 x 16.00 amu SO2 SO2 64.07 amu Molecular mass (or molecular weight) is the sum of the atomic masses (in amu) in a molecule. For any molecule molecular mass (amu) = molar mass (grams) 1 molecule SO2 = 64.07 amu 1 mole SO2 = 64.07 g SO2

  11. 8 mol H atoms 6.022 x 1023 H atoms 1 mol C3H8O x x x = 1 mol C3H8O 1 mol H atoms 60 g C3H8O How many H atoms are in 72.5 g of C3H8O ? 1 mol C3H8O = (3 x 12) + (8 x 1) + 16 = 60 g C3H8O 1 mol C3H8O molecules = 8 mol H atoms 1 mol H = 6.022 x 1023 atoms H 72.5 g C3H8O 5.82 x 1024 atoms H

  12. 1Na 22.99 amu NaCl 1Cl + 35.45 amu NaCl 58.44 amu Formula mass is the sum of the atomic masses (in amu) in a formula unit of an ionic compound. For any ionic compound formula mass (amu) = molar mass (grams) 1 formula unit NaCl = 58.44 amu 1 mole NaCl = 58.44 g NaCl

  13. 3 x 40.08 3 Ca 2 P 2 x 30.97 8 O + 8 x 16.00 What is the formula mass of Ca3(PO4)2 ? 1 formula unit of Ca3(PO4)2 310.18 amu

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