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Elements and Compounds
Compounds
Elements and Compounds
• Many compounds from same elements
• Properties of elements ≠ properties of compounds
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Diatomic Elements
Ionic vs. Molecular Compounds
“Blausen 0660 NaCl” by BruceBlaus is licensed under CC BY 3.0.
“Burning gas stovetop in darkened room” by Derrick Coetzee is licensed under CC BY 2.0.
• Molecules
• Compounds
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Which of the following is a
molecular compound?
a.
b.
c.
d.
e.
Aluminum, Al
Aluminum chloride, AlCl3
Chlorine, Cl2
Carbon monoxide, CO
Cobalt, Co
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Types of Chemical Bonds
Compounds
Chemical Bonds
• Compounds are made of atoms held together by
bonds
• Bonds are forces of attraction between atoms
• Results from attractions between protons and
electrons
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“Periodic Table Large” is licensed under CC BY 3.0.
Metals
Non-metals
Ionic bonding
“NaCl ionic bond” by Mhowison is used under public domain.
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Covalent bonding
“ArCovalent” by Jak is used under public domain.
Identify the group that contains only
substances with covalent bonds.
a. NaCl, CO2, H2
b. CO, H2O, Cl2
c. KCl, MgBr2, Na2O
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Chemical Formulas
Compounds
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Chemical Formulas
• Express the composition of molecules and ionic
compounds in terms of chemical symbols
• Examples:
H2O
NaCl
C2H4
C4H8
C6H6
Chemical Formula Empirical Formula
H2O
NaCl
C2H4
C4H8
C6H6
• Shows elements and simplest whole-number ratio
of their atoms
Which one correctly pairs the
chemical and empirical formulas?
a.
b.
c.
d.
C3H8, CH
C6H12, C3H6
C4H10, C2H5
C6H10, CH2
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Structural Formulas
Ball and Stick Models
Space-filling Models
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Formulas of Ionic Compounds
Compounds
Ionic Compounds
• Ionic compounds usually do not exist as discrete
molecules
• The formula is usually the same as the empirical
formula
• Arranged in a 3-dimensional network
Sodium Chloride (NaCl)
“Blausen 0660 NaCl” by BruceBlaus is licensed under CC BY 3.0.
“Sodium chloride crystal” from www.wikepedia.org is used under public domain.
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How do we figure out what the
formulas are?
Cartoon by Nick D Kim, scienceandink.com. Used by permission.
Ionic Compounds
• Formed from
•
•
Types of Ions
• Charge
– Cations
– Anions
• Size
– Monatomic
• Main group
• Transition element
– Polyatomic
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Main Group Ions
“Periodic Table Large” is licensed under CC BY 3.0.
lithium and chlorine
“Periodic Table Large” is licensed under CC BY 3.0.
magnesium and bromine
“Periodic Table Large” is licensed under CC BY 3.0.
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What is the formula for the ionic
compound formed from aluminum
and sulfur?
a. Al3S2
b. Al2S3
c. AlS
Transition Metals
“Periodic Table Large” is licensed under CC BY 3.0.
Transition Metal Ions
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
+1
+3
+2
+2
+2
+2
+2
+2
+2
+2
+3
+3
+3
+3
+3
+3
+3
+3
+4
+4
+5
+2
+4
+5
+6
+6
+6
+7
Ag+, Zn2+, Sc3+
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Polyatomic Ions
•
•
•
•
•
Sulfate, SO42Nitrate, NO3−
Carbonate, CO32Ammonium, NH4+
Hydroxide, OH−
http://www.studystack.com/flashcard-907510
Parentheses in formulas with
polyatomic ions
• barium hydroxide
– Ba(OH)2
• sodium sulfate
– Na2SO4
• aluminum sulfate
– Al2(SO4)3
What is the formula for magnesium
nitrate? Nitrate = NO3¯
a.
b.
c.
d.
MgNO6
MgN2O6
MgNO3
Mg(NO3)2
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Nomenclature
Compounds
Nomenclature
• Systematic method for naming compounds
• Organic Compounds
–
• Inorganic Compounds
–
Identify all of the inorganic
compounds.
a.
b.
c.
d.
e.
f.
C4H10
HCl
C3H6O
NaCl
CO2
C6H6
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Organic Compounds
methylhexane
Type of Compound
Suffix
Example
Alkene
-ene
propene
Alcohol
-ol
ethanol
Aldehyde
-al
ethanal
Ketone
-one
propanone
(acetone)
Structure
Inorganic Compounds
•
•
•
•
Ionic Compounds
Molecular Compounds
Acids and Bases
Hydrates
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Nomenclature of Ionic
Compounds
Compounds
Ionic Compounds (Monatomic ions)
• Metals which become cations have the same name
as the element
• Nonmetals which become anions take an “-ide”
ending
Naming Ionic Compounds
• Cation, then anion
– Examples:
RbBr
AlF3
NH4CN
K2Cr2O7
“Potassium-dichromate-sample” by Benjah-bmm27 is used under public domain.
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Use Roman numerals for metals with
more than one possible charge
copper(I) chloride
copper(II) chloride
• Exceptions: Ag+, Zn2+, and Sc3+
“Copper(I)-chloride-sample” by Benjah-bmm27 is used under public domain.
“Chlorid měďnatý” by Ondřej Mangl is used under public domain.
What is the IUPAC name for
Fe2O3?
1.
2.
3.
4.
Iron oxide
Iron(II) oxide
Iron(III) oxide
Iron(I) oxide
“Iron oxide red y” by FK1954 is used under public domain.
Hydrates have a specific number
of water molecules attached
cobalt(II) chloride
CoCl2
cobalt(II) chloride hexahydrate
CoCl2·6H2O
“Cobalt(II) chloride” and “Cobalt(II) chloride hexahydrate” by Walkerma are used under public domain.
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Bases named like other ionic
compounds
• Substance that yields hydroxide ions (OH-) when
dissolved in water
• Add “hydroxide”
• Examples:
“Sodium hydroxide” by Walkerma is used under public domain.
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Nomenclature of Molecular
Compounds
Compounds
Molecular Compounds
•
•
•
•
Commonly called covalent compounds
Contain discrete molecular units
Usually composed of non-metallic elements
Most are binary compounds (contain two
elements)
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Naming Molecular Compounds
• First element, then second element
• 2nd gets “-ide” ending
– Example:
CO Carbon monoxide
• Prefixes for number of each element
– Example:
N2O4 Dinitrogen tetroxide
Prefixes
•
•
•
•
•
Mono
Di
Tri
Tetra
Penta
1
2
3
4
5
•
•
•
•
•
Hexa
Hepta
Octa
Nona
Deca
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7
8
9
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Prefix Guidelines
• “mono” may be omitted for the first element
– Example:
CO
• For oxides, prefixes ending in “a” drop it
– Example:
N2O4
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• SO3
• Carbon
tetrachloride
• P4S10
What is the IUPAC name for
SF6?
a.
b.
c.
d.
monosulfur hexafluoride
monosulfur heptafluoride
sulfur hexafluoride
sulfur heptafluride
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Nomenclature of Acids
Compounds
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Naming Binary Acids
• Substance that yields hydrogen ions (H+) when
dissolved in water
• Add “hydro” as prefix
• Add “ic” as suffix
• Examples
o HF
hydrofluoric acid
o H2S hydrosulfuric acid
Oxyacids
Sulfuric acid, H2SO4
Nitric acid, HNO3
Naming Oxyanions
Hypo ________ ite
2 less oxygens than
“ate” compound
________ ite
1 less oxygen than
“ate” compound
________ ate
MEMORIZE
Per ________ ate
1 more oxygen than
“ate” compound
Ions will all have the same charge
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Oxyanion Example
Hyposulfite
Sulfite
Sulfate
SO42-
Persulfate
Shows the naming trend,
doesn’t mean ion is commonly seen.
Oxyacids
Anion
Acid
Hypo ________ ite  Hypo ________ ous acid
________ ite

________ ous acid
________ ate

________ ic acid
Per ________ ate

Per ________ ic acid
Oxyacid Example
Hyposulfurous acid
Sulfurous acid
Sulfuric acid
Persulfuric acid
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What is the IUPAC name for
HI(aq)?
a.
b.
c.
d.
hydroiodic acid
hydroiodous acid
hydroiodic acid
iodic acid
What is the IUPAC name for
the acid formed from PO33-?
a.
b.
c.
d.
phosphoric acid
perphosphoric acid
hypophosphous acid
phosphorous acid
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Molar Mass of Compounds
Compounds
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Atomic Mass
Molecular Mass
• Mass of a single atom of
an element
• Units of amu
• Mass of single unit of a
compound
• Also known as
– Formula mass
– Molecular weight
• Units of amu
“Periodic Table Large” is licensed under CC BY 3.0.
Molecular Mass of MgCl2
“Salt truck Milkwaukee” by Smmurayinchester is licensed under CC BY 2.0.
Molecular Mass of H2SO4
2H
1S
4O
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Molecular Mass of C4H9OH
4C
10 H
1O
What is the molecular mass of
(NH4)2Cr2O7?
a.
b.
c.
d.
238.07 amu
252.08 amu
234.04 amu
246.04 amu
“Ammonium-dichromate-sample” by Benjah-bmm27 is used under public domain.
Molar Mass
One molecule of H2O
18.02 amu
One mole of H2O
18.02 g/mol
“mol_of_water2” by asoult is licensed under CC BY 2.0.
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Use Molar Mass in Calculations
• Like conversion factors (100 cm = 1 m, 12 in = 1
ft), molar mass can be used in calculations
• Molar mass has the units of
How many moles are in 34.2 g of
H2O?
How many grams of C3H8
(propane) are present in 4.32 moles
of C3H8?
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How many moles of caffeine
(C8H10N4O2, 194.19 g/mol) are
found in a 50.0 g sample?
a.
b.
c.
d.
0.257 mol
3.88 mol
0.971 mol
0.244 mol
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Percent Composition by
Mass
Compounds
Percent Composition
Mass percent of each element
in a compound
%
part
100
whole
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Calculating Mass Percent
mass % of element 
n  molar mass of element
 100
molar mass of compound
n = number of moles of the element in
1 mole of the compound
Example: for the O in CO2, n = 2
Determine the mass percent of
carbon and hydrogen in C4H10
(58.12 g/mol).
What is the mass percent of
potassium in K3PO4?
a.
b.
c.
d.
18.42 %
45.43 %
55.26 %
29.09 %
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Mass Percent as Relationship
• CaCO3 is 40.04 % Ca by mass
What mass of calcium is found
in 225 g CaCO3?
What mass of potassium is
found in 75.0 g of K3PO4?
a.
b.
c.
d.
39.1 g
41.4 g
33.6 g
19.7 g
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Relationships from Chemical
Formulas
Compounds
Atoms & Molecules
H2 O
• 1 molecule water
contains
– 2 atoms of H
– 1 atom of O
Bike
• 1 bike contains
– 2 wheels
– 1 frame
Atoms & Molecules
H2 O
Bike
• 1 mole of water contains
• 1 mole of bikes contains
– 2 moles of H atoms
– 1 mole of O atoms
– 2 moles of wheels
– 1 mole of frames
“Amadeo Avogadro” is used under public domain.
“mol_of_water2” by asoult is licensed under CC BY 2.0.
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How many Cl atoms are present in
25.1 g of AlCl3?
If there are 4.7 x 1025 atoms of
phosphorus in a sample of
potassium phosphate, then
what is the mass of potassium
phosphate?
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What is the formula for
potassium phosphate?
a.
b.
c.
d.
K3PO4
KPO4
K(PO4)3
K2PO4
What is the molar mass of
K3PO4?
If there are 4.7 x 1025 atoms of
phosphorus in a sample of
potassium phosphate, then what is
the mass of potassium phosphate?
a.
b.
c.
d.
0.36 g
2.7 g
1.7 x 104 g
6.4 x 105 g
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Conversions Between
gram
mol
↔ mol
molar mass
↔ actual
gram
↔ mL
use this tool
number
(or cm3)
gram ↔ kilogram (example)
molecules ↔ atoms
Avogadro’s No.
density
prefix meaning
subscripts
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Chemical Formulas from
Experimental Data
Compounds
Determining formula from mass
percent
• Experimental data gives mass percent of each
element
• Determine empirical formula
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Determination of Empirical
Formula
1. If starting with mass percent of each element,
assume 100 g sample and convert percent to
mass.
2. Convert mass of an element to moles of an
element.
3. Divide by smallest number of moles.
4. Determine subscripts.
Phenol, a general disinfectant, has the
composition 76.57% C, 6.43% H, and
17.00% O, by mass. Determine its
empirical formula.
1. Assume 100 g and
covert to mass.
2. Mass to moles.
3. Divide.
4. Determine
subscripts.
Diethylene glycol, used as an antifreeze, has
the composition: 45.27% C, 9.50% H, and
45.23 % O, by mass. If we assume a 100.0 g g
sample, what is the mass of carbon?
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Determination of Molecular
Formulas
• Molecular formula can be determined from the
empirical formula.
• Need approximate molar mass for the compound
The empirical formula of
hydroquinone, a chemical used in
photography, is C3H3O, and its
molecular mass is 110 amu. What
is its molecular formula?
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