Transcript Chapter #7 Notes

Chapter
#7
Chemical
Formulas
and
Chemical
Compounds
NearingZero.net
Section 1
Chemical Names and Formulas
• Chemical Formulas
• C6H12O6
Subscript indicates
that there are 6
carbon atoms
Al2(SO4)3
Monatomic Ions
• Positive Ions
1. Write the name of the
element
2. Write the word ion
• Na+ = Sodium ion
• Transition elements
use Roman Numerals
• Fe +2 = Iron (II) ion
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1.
Negative Ions
Write the name of
the element
2. Change the ending to
–ide
3. Write the word ion
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Cl- = Chloride ion
Binary Ionic Compounds
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2.
3.
2 elements= Binary
Metal + nonmetal = ionic
Write the name of the 1st element
Write the name of the 2nd element
Change the ending to –ide
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NaCl = Sodium Chloride
MgCl2 = Magnesium Chloride
Stock System
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Uses roman numerals
1. Write the name of the 1st element
2. Write the oxidation number of the 1st
element
3. Write the name of the 2nd element
4. Change the ending to –ide
• CrF3 = Chromium (III) Flouride
• NiF
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Binary Molecular Compounds
Molecular= covalent PG 212 Prefixes
Write the name of the 1st element
Write the name of the 2nd element
Change the ending to –ide
Put in prefixes
Only use prefixes on the 1st element if it is
more than 1
NO2= Nitrogen Dioxide
N2O3
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Binary Acids
Acids always begin with H
Acids that consist of 2 elements
Write hydro
Write the 2nd element
Change the ending to –ic
Write the word ACID
HF= Hydrofluoric Acid
HBr
Oxyacids
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Are acids that contain hydrogen, oxygen, and a
third element.
 Never use Hydro
1. Write the name of the polyatomic (pg 210)
2. Change the ending to –ic or –ous (ate -ic & ite
–ous)
1. Write the word ACID
• H2SO4 = sulfuric acid
• H3PO4
Polyatomic Compounds
1. Write the name of the 1st element
2. Write the name of the polyatomic (pg
210)
• NaNO3 = Sodium Nitrate
• AgNO2
Section 2 Oxidation
Numbers
• Oxidation numbers- are assigned to the
atoms in molecules, including molecular
ions, to show the general distributions of
electrons among the bonded atoms.
+1
+/-
+2
+3 4 -3 -2 -1
Oxidation numbers
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3.
Rules pg 216
UF6
UF6 criss cross the numbers up
Check the 2nd element using the periodic table
U= +6 F= -1
Polyatomic compounds do a math line
+3 -8 =0
H= +1 P= 5 O=-2
+1 -2
H3PO4
If there is an ION (charge) do a math line
Practice oxidation
numbers
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GeCl2
CS2
ClO3H2SO4
PCl3
HNO3
GeO
SO4-2
NO2-
Section 3 Using Chemical
Formulas
• Formula mass (molar mass or weight) of
any compound or polyatomic ion is the sum
of the average atomic masses of all the
atoms represented in the formula.
• H20 H x 2= 2.014g
O x 1 = 15.999g
18.013 g of H2O
Old stuff
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Mole to grams
Grams to moles
Moles to particles
Particles to moles
Grams to particles
Particles to grams
Percent Composition
% comp= Mass of element in the sample
mass of sample (formula mass)
Calculate the % comp of H2O
X 100
Section 4 Determining
Chemical Formulas
• Empirical Formula- (simplest formula)
consists of the symbols for the elements
combined in a compound, with subscripts
showing the smallest whole-number mole
ratio of the different atoms in the
compound.
• C2H6 simplest formula would be CH3
Empirical Formulas
1. Drop the % signs and add grams
2. Covert to moles of each element
3. Take the smallest number of moles and
divide it into all the other values
4. Write the formula
Determine the empirical formula for a
sample that contains 78.1% B & 21.9% H
Molecular Formulas
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5.
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8.
Do the same 4 steps for determining
empirical formulas
Add up the formula mass of the empirical
formula
Use the molecular formula mass in the
question
Use the formula X= Molecular formula mass
empirical formula mass
Use the x and multiply your empirical
formula using it
• “Cartoon”. Aug. 11, 2006.
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