Isotope Practice sodium Na 11 protons, 11 electrons, 12 neutrons copper Cu 29 protons, 29 electrons, 35 neutrons silver Ag 47 protons, 47 electrons, 61 neutrons

Charge Practice Na protons, 10 electrons, 12 neutrons Cl protons, 18 electrons, 20 neutrons Sr protons, 36 electrons, 50 neutrons

How did you do on the last two slides? Remember, protons # = atomic # Neutrons = Mass # - proton # Electrons = Proton # - (charge) –Keep the + or – in the charge

Avg. Atomic Mass? Average Atomic Mass is… - weighted average of the atomic of the naturally occurring isotopes. IsotopesMass Number % abundance Avg. Atomic Mass Carbon % Carbon % Carbon-1414trace

The math for weighted average Take the % and change it back to a number Multiply it by the mass # Do this to each mass # isotope, then add together. 12 x = x = Add these two together and you get Look on the periodic table for Carbon – note the weighted atomic average – it’s !! If there were 3 isotopes, you would do the same and then add the 3 numbers together. Then you can check your answer on the period table.

htd_mole.html

What is a Mole? A mole is… - SI unit for amount of substance - Avogadro’s Number -> x particles/mole - this is the # of atoms contained in exactly 12 g (1 mole) of carbon. An amount – like 12 eggs in 1 dozen !

What is a Molar Mass? Molar mass is… - the mass of 1 mole of substance For example: 1 mole of carbon has a mass of g 1 mole of silicon has a mass of g 1 mole of gold has a mass of g

To think about If you had 1 dozen chicken eggs (12) and compared them to 1 dozen ostrich eggs (12 also of those), they weigh different amounts. SAME with the mole. 1 mole (6.022 x atoms) of Carbon weighs less then 1 mole (6.022 x atoms) of gold (gold atom is bigger)

Units and the Periodic Table Masses reported in the Periodic Table can be used two ways: - a special unit just for atoms called an atomic mass unit (amu). - one mole of substance has a mass in grams exactly equal reported in the Periodic Table (g/mol).

Conversions Diagram Amount of Element in Moles Number of Atoms in Element Mass of Element in Grams Molar Mass Avogadro’s #

Conversion Practice 1.Moles in g Al? Grams in 1.51 moles Cu? -> 4.00 mol Al -> grams Cu g Al____1mole Al_____ g Al moles Cu___ __ g Cu 1 mole Cu

You do the next two Don’t look at my answers until you do the next two conversion problems just like my examples.

Conversion Practice 3.Grams in 0.5 moles Ag? 4.Moles in 124 g Mg? -> 53.9 grams Ag -> 5.1 mole Mg 0.5 moles Ag_____ _________ 124 g Mg___ ______________ 1mole Ag g Ag g Mg 1mole Mg

Counting Atoms 1) Subscripts on an element, only apply to that element C 6 H 12 O 6 6 carbons 6 oxygens 12 hydrogens

You do the next one Don’t look at my answer until you do try to figure out the number of each type of atom

Counting Atoms 2) Subscripts on a set of ( ), apply to all atoms in the ( ). Fe 2 (SO 4 ) 3 2 irons 12 oxygens 3 sulfurs

For parenthesis – you multiply Just in case you didn’t get 12 oxygen, you multiply the number on the outside of the parenthesis with the numbers inside.

Molar Mass Molar mass (Formula weight) of a molecule… - sum of all atomic masses For example: 1 mole of H 2 O has a mass of: H = g x 2 = g O = g H 2 O = or 18 g

You do the next two Don’t look at my answers until you do the next two molar mass problems just like my example for water. Note, anytime you get average atomic mass (g) off the periodic table, you have ONE mole. Same with a compound. All those numbers for water were from the periodic table, so 18 grams water = 1 mole

Molar Mass 1 mole of NaCl has a mass of 1 mole of SiO 2 has a mass of Na = 23 g Cl = 35.5 g NaCl = 58.5 g Si = 28.1 g O = 16 g x 2 = 32 g SiO 2 = 60.1 g

You do the next four Don’t look at my answers until you do the next four molar mass problems just like my examples.

Molar Mass Practice Calc. Molar Mass of the following: H 2 O 2 (hyd. peroxide) CH 3 OH (methanol) Ca(NO 3 ) 2 (calcium nitrate) Fe 3 (PO 4 ) 2 (Iron II Phosphate) -> g/mol -> g/mol -> 174 g/mol -> g/mol

Grams-to-Moles Water-->H 2 O Calculate the following: Moles of water in 50 grams -> 2.8 mole H 2 O ________ ____________ _____ 50 g H 2 O 18 g H 2 O 1 mole H 2 O

You do the next one Don’t look at my answer until you do the next conversion problem just like my last example with water. Must first do molar mass, then a T chart.

Grams-to-Moles Ibuprofen-->C 13 H 18 O 2 Calculate the following: Molar mass of Ibuprofen ________ g/mol Moles Ibuprofen in one bottle (33g) _______ mol C 13 H 18 O 2 -> > 0.16

Counting Atoms 1) Subscripts on an element, only apply to that element C 6 H 12 O 6 ___carbons __ oxygens ___ hydrogens

Counting Atoms 2) Subscripts on a set of ( ), apply to all atoms in the ( ). Fe 2 (SO 4 ) 3 __irons ___ oxygens __ sulfurs

Molar Mass Molar mass (Formula weight) of a molecule… - sum of all atomic masses For example: 1 mole of H 2 O has a mass of: H = g x 2 = g O = g H 2 O = or 18 g

Molar Mass 1 mole of NaCl has a mass of 1 mole of SiO 2 has a mass of Na = ___ g Cl = g NaCl = ____ g Si = ___ g O = g SiO 2 = ____ g

Molar Mass Practice Calc. Molar Mass of the following: H 2 O 2 (hyd. peroxide) CH 3 OH (methanol) Si 3 N 4 (silicon nitride) Si(OCH 2 CH 3 ) 4 (TEOS) -> ____ g/mol -> _____ g/mol

Grams-to-Moles Water-->H 2 O Calculate the following: Moles of water in 50 grams -> ____ mole H 2 O ________ ____________ _____ 50 g H 2 O 18 g H 2 O 1 mole H 2 O

Grams-to-Moles Ibuprofen-->C 13 H 18 O 2 Calculate the following: Molar mass of Ibuprofen Moles Ibuprofen in one bottle (33g) -> _____ g/mol -> _____ mol C 13 H 18 O 2