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The Mole

The Mole. Unit 3. The Mole. So far we have been dealing with numbers on the atomic scale… Atomic Number = # of protons Mass Number = # of protons + # of neutrons Atomic Mass = # of amu in one average atom. The Mole. This is a really small scale.

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The Mole

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  1. TheMole Unit 3

  2. The Mole • So far we have been dealing with numbers on the atomic scale… • Atomic Number = # of protons • Mass Number = # of protons + # of neutrons • Atomic Mass = # of amu in one average atom

  3. The Mole • This is a really small scale. • Is it logical to try to measure out chemicals for labs this way? • NO! • We need a bigger scale to use for everyday measurements and calculations.

  4. The Mole • We need… • The MOLE! • The MOLE is a unit of measure – a unit of “how many”.

  5. The Mole • Just like a dozen eggs tells us “how many” eggs, a mole tells us “how many” particles. • 1 dozen eggs = 12 eggs • 1 mole = 6.02 x 1023 particles • Particles can be anything – atoms, molecules, eggs, etc.

  6. The Mole • This number (6.02 x 1023) is called Avogadro’s Number, in honor of Amedeo Avogadro’s contributions to chemistry. • Unfortunately for him, his ideas weren’t really recognized as important until after he died.

  7. The Mole • But wait, where did we get this number? • Scientists have found that there is exactly 1 mole of atoms in the atomic mass of an element when that mass is expressed in grams. • Huh?

  8. The Mole • For example: • What is the atomic mass of C-12? • (Hint – there is only one isotope here, so think mass number) • Atomic mass = 12 amu

  9. The Mole • Then express that mass in grams  12 g • In exactly 12 grams of C-12, there is one mole (6.02 x 1023) of atoms. • This also works for our average atomic masses (from the periodic table).

  10. The Mole • So, in exactly 12.01 g of natural carbon there are 6.02 x 1023 atoms. • AND, 6.02 x 1023 atoms = 1 mole. So 1 mole of carbon = 12.01 g. • Hmm…..those sounds suspiciously like conversion factors… • Time for examples!

  11. The Mole • How many atoms are in 1.00 mole of gold? 6.02 x 1023 atoms 6.02 x 1023 Atoms Au 1.00 mole Au = 1 mole

  12. The Mole • How many molecules are in 2.00 moles of water? 6.02 x 1023 molecules 1.20 x 1024 Molecules H2O 2.00 mole H2O = 1 mole

  13. The Mole • How many marbles are in 1.00 mole of marbles? (Enough to cover the entire Earth to a depth of 50 miles!) 6.02 x 1023 marbles 1.00 mole marbles = 1 mole 6.02 x 1023 marbles

  14. The Mole • How many grams are in 1.00 mole of neon? 6.02 x 1023 atoms 20.18 g Ne 1.00 mole Ne 1 mole Ne 6.02 x 1023 atoms = 20.2 g Ne

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