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AP Chemistry
Atomic Theory
Neon­20 through the eyes of...
DALTON
RUTHERFORD
Nuclide Symbol:
20
10
Ne
What is an isotope???
atoms whose nuclei have the same number of protons, but different numbers of neutrons
same atomic number, different mass numbers
Unit 1
AP Chemistry
ATOMIC MASS
What is the atomic mass of Chlorine
with the following isotopic information:
Chlorine­35
34.96885 amu
75.771% abundance
Chlorine­37
36.96590 amu
24.229% abundance
Chlorine­35 = 26.49625 Chlorine­37 = 8.956468
Periodic Table
Unit 1
35.45272 amu
AP Chemistry
Molecular Compounds
Composed of molecules, all of which are alike
Small! One billionth of a drop of water has 1 trillion molecules!!!
Formula gives the EXACT amount of the atoms
of an element in the molecule
CH3Cl = 1 carbon, 3 hydrogen, 1 chlorine
Some elements actually exist in nature as
diatomic molecules
H2
O2 F2 Br2 I2
N2 Cl2 S8
Molecular Compounds pgs. 65­66
Formulas and Names
Unit 1
trisulfur
octafluoride
carbon
tetranitride
Cl2O6
PBr5
AP Chemistry
Ionic Compounds
Ions are electrically charged particles obtained from an atom or a chemically bonded group of atoms by adding or removing electrons
Cations = positive
Anions = negative
Ionic compounds are composed of cations and anions, and their formulas are formula units showing the ratio of those ions
MONATOMIC IONS
POLYATOMIC IONS
Ionic Compounds
Formulas and Names
aluminum bromide
copper (II) sulfide
magnesium nitrate
Unit 1
iron (III) carbonate
AP Chemistry
Ionic Compounds
Formulas and Names
BaO
K3PO4
MnSO4
AgCl
HYDRATES
Compounds containing water molecules weakly bonded in their crystals
What is the percentage of water in a sample of Epsom salts when its mass was 2.25 g before dehydration, and 1.07 g after?
Unit 1
AP Chemistry
Chemical Reactions
reactants
products
(s) = solid (l) = liquid
(g) = gas
(aq) = aqueous (water) solution
A chemical formula or a can be above arrow
representing the use of a catalyst or heat Reactions must be balanced so that the numbers of atoms of each element are equal on both sides
Law of Conservation of Mass!
Balance Chemical Reactions
Al + CuCl2
AlCl3 + Cu
As2S3 + O2
As2O3 + SO2
Ca3(PO4)2 + H3PO4
Unit 1
Ca(H2PO4)2
AP Chemistry
Interpret a Balanced Equation
Molecular, Molar and Mass
Interpretations
N2 (g) + 3 H2 (g)
2 NH3 (g)
Molar Mass and Moles
The molar mass of a substance is the mass of one mole of the substance!
It is in g/mol and is numerically equal to the formula mass in amu!
H 2O
Unit 1
NaCl
Fe2(SO4)3
AP Chemistry
Molar Conversions
How many moles of nitric acid are in a 28.5 g sample?
HNO3
How many grams of hydrogen peroxide are in 0.909 mol?
H2O2
How many molecules are in a 3.46 g sample of
hydrogen chloride?
HCl
% Mass
What is the mass percentages of the elements in ammonium nitrite to 3 sig figs?
NH4NO2
%N = %H = %O = How many grams of Hydrogen
are in 58.2 g of ammonium nitrite?
Unit 1
AP Chemistry
% C,H,O
Empirical and Molecular Formulas
8.48 g of a compound containing only C, H and O is completely burned. It gives off 12.42 g of carbon dioxide and 5.08 g of water. What is the mass percentage of each element in this compound?
% C,H,O
Empirical and Molecular Formulas
What is the empirical formula of this compound?
This compound is lactic acid with a molecular mass of 90.0 amu. What is lactic acid's molecular formula?
Unit 1
AP Chemistry
STOICHIOMETRY!
Al2(CO3)3 → Al2O3 + 3 CO2
If 9.66 mol of CO2 is produced, how many moles of Al2(CO3)3 were there to start?
Al2(CO3)3 → Al2O3 + 3 CO2
If 85.96 g of Al2(CO3)3 decomposes, how many grams of CO2 will be given off?
In an experiment, 12.07 g of sodium was heated with 17.89 g of chlorine to produce sodium chloride.
Assume these substances react according to the following balanced equation:
2 Na + Cl2 → 2 NaCl
a) How many grams of sodium chloride should theoretically be produced?
b) Experimentally, it is determined that 25.75 g
of sodium chloride is actually produced. What was the percentage yield of this reaction?
Unit 1