We frequently refer to measures casually… Couple Few Dozen Baker’s Dozen Ream LORD

 We can’t work with individual atoms or atomic mass units in the LAB  – Because we can’t see things that small we work with samples large enough for us to SEE and WEIGH on a balance using units of grams.

Billions of atoms are hard to keep track of in calculations A pile of atoms big enough for us to see contains billions of atoms.

It represents a number of ‘things, just like a dozen In honor of Amedeo Avogadro, Italian chemist ( ) x is referred to as Avogadro’s Number (N A ) 1 mole (unit: mol) = 6.02 x atoms (symbol: n)(or molecules)

This is a HUGE number!!!! 1 mole = 6.02 x particles, molecules, atoms. 1 dozen eggs =12 Eggs 1 mole of eggs = 6.02 x Eggs

A mole of marbles would cover the entire Earth’s surface 50 MILES DEEP!!!!

 If you spent a BILLION DOLLARS every SECOND, you couldn’t spend a mole of dollar bills in your lifetime!!!

 If you were able to count at the rate of 1 million numbers a second, it would take about 20 billion years to count out one mole.

Molecules – covalently bonded compounds. Usually a non-metal and a non-metal. The molecule of water is the particle that is counted. 1 mole of water has 6.02 x molecules/mol.

Formula Units– ionically bonded compounds. Usually a metal and a non-metal The formula unit of salt is the particle that is counted 1 mole of salt has 6.02 x formula units/mol

Atoms– elemental. Found on the PT of E, but not part of HOFBrINCl. The atom of copper is the particle that is counted. 1 mole of copper has 6.02 x atoms/mol

Identify the unit for each substance. a)Methane (CH 4 ) b)Magnesium chloride c)Aluminum d)Butane (C 4 H 10 ) e)Hydrogen peroxide f)Sodium nitrate g)Calcium a)molecule b)F.U. c)atoms d)molecule e)molecule f)F.U. g)atoms

 A “dozen” is an easy way to say “12”.  A “mole” is an easy way to say “6.02 x 10 23”

MOLE Particles (molecules F.U. Atoms) X ÷ Avogadro’s Number

N = n x N A = (0.50 mol)(6.02 x molecules/mol) = 3.01 x molecules There are 3.01 x molecules of methane

N = n x N A = (1.25 mol)(6.02 x molecules/mol) = x molecules There are 7.52 x molecules of carbon dioxide.

n = N/N A = 5.83 x molecules 6.02 x molecules/mol n = 9.68 mol Therefore there are 9.68 mol.

n = 3.57 x atoms 6.02 x atoms/mol n = 59.3 mol Therefore there are 59.3 mol of zinc.