Download Accelerated Chemistry Chapter 7 Student Notes

Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Chapter 7 problems: page 231 Section Review: 2, 4
page 251 Chapter Review: 1, 3, 4, 6, 16, 17, 23, 24, 33, 36, 37, 42, 50
7.1 Chemical Names and Formulas
Lots of common names:
dry ice , epsom salts , milk of magnesia
chemical formulas show the relative #’s of atoms in a chemical compound
ex.
C12H22O11
Pb(NO3)4
(NH4)2CrO4
monatomic ions – end in “____” – look up charges on periodic table
compare F (
)
to
F-1 (
)
compare S (
)
to
S-2 (
)
Writing Formulas for Ionic Compounds
positive ions -
negative ions -
charges must =
Binary ionic compounds
3 rules(2 for now)
if the charges on the ions are the same, “drop ‘em”
if the charges are different, “criss cross”
charges the same Ex1
Sodium Chloride
Ex2
Magnesium Sulfide
charges different -
O7 Notes - S
Ex3
Sodium Sulfide
Ex4
Magnesium Chloride
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Ternary Ionic compounds
Polyatomic ions - if you take, a polyatomic ion, more than once, use parentheses......
Ex5
Sodium Nitrate
Ex6
Sodium Carbonate
Ex7
Aluminum Nitrate
Ex8
Aluminum Carbonate
Ex9
Aluminum Phosphate
Ex10 Aluminum Bihypophosphite
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Writing Names for Ionic Compounds name front (
), name back (
)
Binary ionic compounds Ex1
NaCl
Ex2
MgCl2
Ex3
Al2O3
Ex4
NaH
“The big lie” ex-
CuCl
Cu = +1
CuCl2
Cu = +2
“So, the new system” - Stock System – use Roman Numerals for naming compounds
with metals that have multiple charges (the transitions!)
Normal Name
Copper
Iron
Lead
Tin
Mercury
Symbol
Charge
+1
+2
+2
+2
+1
Stock Name
Cu ( )
Fe ( )
Pb ( )
Sn ( )
Hg ( )
Charge
+2
+3
+4
+4
+2
Stock Name
Cu ( )
Fe ( )
PB ( )
Sn ( )
Hg ( )
notable exceptions –
O7 Notes - S
Ex5
Sn3N2
Ex6
AgOH
Ex7
Ag2CO3
Ex8
Zn(OH)2
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Ex9
ZnSO3
Ex10 Cu(HSO2)2
Ex11 CuSO2
Ex12 CuHSO2
Ternary ionic compounds - 3 or more elements make up the compound
Ex13 LiClO3
Ex14 LiClO2
Ex15 CaCO3
Ex16 Ca(HCO2)2
Ex17 Fe(NO3)3
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Writing Names for Molecular Compounds
we use prefixes
molecular =
**
1=
2=
3=
5=
don’t use the prefix
Ex1
Ex2
Ex3
4=
6=
on the first atom
CO
Ex4
CBr4
Ex5
N2O5
Ex6
SF6
CO2
PCl3
Writing Formulas for Molecular Compounds
The prefixes = the
.
Do not look at the
.
Ex7
Sulfur Dioxide
Ex8
Disulfur Trioxide
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Writing Names for Acids –
we’ll do this in chapter 16 (again)
Acid - when a solution yields H+ ions in solution
2 types - binary and ternary (sometimes called oxy)
binary -
H and one other type of atom
name them
Ex1
HCl
Ex2
HBr
Ex3
HF
Ex4
H2S
Ex5
H3P
hydro
ic acid
Writing formulas from names for Acids - use the “criss-cross applesauce” rules.
Ex6
Hydronitric Acid
ternary (oxy) –
acids that have H with a
ion
Do not start with
Change the –ate ending to
Change the – ite ending to
Ex7
O7 Notes - S
H2SO4
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Ex8
H2SO3
Ex9
HClO4
Ex10 HClO3
Ex11 HClO2
Ex12 HClO
When writing formulas from names, use the “criss-cross applesauce” rules.
Ex13 Nitric Acid
Ex14 Phosphorous Acid
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
7.2 Oxidation numbers
Since electrons are shared, there is no
- we assign the more
electronegative element the “
” negative charge - this is known as the oxidation #
- oxidation numbers can also be positive.
oxidation # - a number assigned to an atom to show the
Rules for assigning oxidation #’s
1. Free elements =
2. Oxidation #’s of ions =
3. F =
4. 0 =
(usually - except in peroxides, O =
5. H =
)
(usually - except in metal hydrides, H =
)
6. more electronegative atom gets a
7. Ox #’s add up to
8. Ox #’s = the
Ex1
O7 Notes - S
in compounds
in
FeO
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
O7 Notes - S
Ex2
Fe2O3
Ex3
H2SO4
Ex4
H2SO3
Ex5
H2Cr2O7
Ex6
NO3 –1
Ex7
NO2 -1
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
7.3 Using Chemical Formulas
Be able to calculate molar mass (aka – formula mass, molecular weight,
atomic weight, atomic mass, gram formula weight, etc.)
Add atomic weights from the periodic table
Ex1
H2
Ex2
H2O
Ex3
Ca(OH)2
.
don’t forget hydrates! MgSO4 7 H20 =
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Be able to convert between grams, moles, particles, and liters
Mole Relationships - For starters in chemistry, we have to be able to convert between
moles, grams, and molecules/atoms of substance (also liters when we work with gases)
use the “mole map
The Gram House
The Mole House
The Particle House
Use the Ptable to determine
the number of grams
Always a value of:
Always a value of:
1.0 Mole
6.02 x 1023 atoms or
molecules
The House of Volume
For gases, use 22.4 Liters at
Standard Temperature and
Pressure (STP)
Ex1
convert 13.8 g Li to moles
Ex2
convert 2.0 moles Ne to g
Ex3
convert 3.0 moles of Be to atoms
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Ex4
convert 44.8 L of O2 to moles
Ex 5
convert 128 g of O2 to molecules of O2
Ex6
convert 128 g of O2 to atoms of oxygen
Ex7
If there are 9.71 x 1024 atoms of oxygen in a sample of SO3, how many grams of
SO3? liters?
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Percentage Composition - every compound has a certain percentage of each type of
atom (we measure it by mass)
% composition = (mass of element/ mass of compound)
x
100
Ex1
Calculate the percent composition if a compound contains 24 g of Carbon and
64 g of Oxygen.
Ex2
What is the percentage composition of each element in Ba(OH)2
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
7.4 Determining a compound’s empirical and molecular
formula
Empirical formula - the lowest whole number ratio of atoms in a compound (simplest
formula)
Three basic types of problems:
1. Divide (%’s or grams) by the
2. Divide the resulting #’s by the
3. Multiply by 2 or 3 only if a
isn’t the result of step 2
Ex1
Calculate the empirical formula if there is 52.17 % C, 13.04% H, and 34.78 % O.
Ex2
Calculate the empirical formula if there is 26.56 % K, 35.41 % Cr, and 38.03 % O.
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Accelerated Chemistry
Chapter 7 Notes – Chemical Formulas and Chemical Compounds
Ex3
Find the empirical formula if a sample contains 5.6 g N and 12.8 g O.
Finding Molecular Formulas:
The same steps as empirical formula with one additional step - use the gram
formula mass of the empirical formula and its relationship to the gram formula
mass of the molecular formula to find what number to multiply the empirical
formula by to find the molecular formula (sounds more complicated than it is).
O7 Notes - S
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