Chemical
Compounds
Honors Chemistry
3 Types of Formulas
• Empirical: Smallest whole-number-ratio of atoms
or ions in a compound
– Ex. CH2
NH3
• Molecular: Tells you the actual number of atoms
of an element in a compound
– Ex. C2H4
N2H6
• Structural: Indicates how the atoms are bonded
to each other
How does the mole relate to
compounds?
REMEMBER
Atoms are too small to count or mass individually.
It is easier to count many or mass many.
amu
gram
(atomic scale)
(macroscopic scale)
mole
atoms, ions, molecules, or formula units
Molar Mass = mass, in grams, per 1 mole of a substance
units = grams/mole (g/mol)
Example: the molar mass of
H2O is
18.0 g/mol
Molecular formulas and molar masses are
used to determine Percent Composition
1. Definition: percentage, by mass, of each element
in a compound
% Composition = (part/whole) x 100
2. Problems
a. Calculate the % composition of NaCl
% Na:
39.3% Na
% Cl:
60.7% Cl
Percent Composition of
Hydrate
Definition: A hydrate is an ionic compound
with water embedded in it.
b.
Calculate the % water in a hydrate, Mg3(PO4)2 . 6H2O.
370.9 g/mol Mg3(PO4)2 . 6H2O
molar mass of hydrate =
molar mass of anhydrate + x(molar mass of water)
% water =
29.1% H2O
How can you identify different types of
compounds?
• Type of Compound Identification
• Ionic
Begins with a metal
• Covalent
Begins with a nonmetal
• Acid
Begins with a hydrogen and is aqueous
• Hydrate
Ionic Compound and Water
Ionic Compounds
• Made from a positively and negatively
charged ion
• Overall charge of the compound is zero
• Types of Ionic Compounds
– Binary
– Ternary
Binary Compounds:
Composed of two
monatomic ions
• Primary Rules for Charges: YOU MUST KNOW THESE RULES
1 or IA
+1
2 or IIA
+2
3 or IIIA
+3
15 or VA
-3 in binary compounds with metals, H, or
NH4+
16 or VIA
-2 in binary compounds with metals, H, or
NH4+
17 or VIIA
-1 in binary compounds with metals, H,
or NH4+
Ionic Compounds – look at charges; roman
numerals needed for elements with more than one
charge (polyvalent)
a. Binary Compounds – only monatomic
ions in compound
sodium chloride
NaCl
iron(III) sulfide
Fe2S3
FeS
iron(II) sulfide
Ionic Compounds
Binary Compounds
HF(g)
hydrogen fluoride
AlCl3
aluminum chloride
Cr2O3
chromium(III) oxide
Ionic Compounds
Ternary Compounds – contain 1/more
polyatomic ions in compound
sodium carbonate
Na CO
2
3
chromium(III) oxalate
Cr2(C2O4)3
ammonium sulfate
(NH4)2SO4
Ionic Compounds
• Ternary
Co3(AsO4)2
CuSO3
cobalt(II) arsenate
copper(II) sulfite
Note for polyatomic ions:
-ate vs. –ite
per- and hypo-
Ionic Compounds
• magnesium hydroxide
• calcium sulfate
• ammonium phosphate
Mg(OH)2
CaSO4
(NH4)3PO4
Anion
Description
Example
per_____ ate
1 extra
oxygen
ClO4-1
perchlorate
_______ate
the most
common form
ClO3-1
chlorate
_______ ite
1 less
oxygen
ClO2-1
chlorite
hypo_____ ite
2 less
oxygens
ClO-1
hypochlorite
Now try these…
• sulfite
SO3-2
• periodate
IO4-1
• phosphite
PO3-3
• bisulfite
HSO3-1
Check for Understanding
• magnesium hydride
• calcium acetate
MgH2
Ca(CH3COO)2
• FeS2O3
iron (II) thiosulfate
• SnI4
tin (IV) iodide
Molecular Compounds – formed
between 2 nonmetals
*Use prefixes
mono = 1
di = 2
tri = 3
tetra = 4
penta = 5
hexa = 6
hepta = 7
octa = 8
nona = 9
deca = 10
Binary Compounds: only 2 elements in the
compound; use prefixes and –ide ending
CCl4
carbon tetrachloride
N2O5
dinitrogen pentoxide
More Practice
• dihydrogen monoxide
• nitrogen tetrabromide
• S2O6
H2O
NBr4
disulfur hexoxide
Hydrates – ionic compound with
water bonded in its structure
anhydrate . xH2O
• anhydrate  ionic compound
• add prefix to indicate # of water
molecules
CuSO4 . 5H2O
copper(II) sulfate pentahydrate
Acids – compounds that produce
hydrogen ions in water
1. Mineral Acids
Binary Acids
1st word:
prefix = hydro
root formed from anion
suffix –ide changed to -ic
2nd word:
acid
a.
HCl(aq)
HBr(aq)
hydrochloric acid
hydrobromic acid
B. Oxyacids
• 1st word: root from anion
Suffix ate changed to ic
Suffix ite changed to ous
**Exceptions: if you have sulf or phos as
roots, change the root to sulfur or
phosphor
• 2nd word: acid
HNO3
HNO2
phosphorous acid
Nitric acid
Nitrous acid
H3PO3
Common Acids to Know
•
•
•
•
•
•
•
hydrochloric acid
HCl
carbonic acid
H2CO3
perchloric acid
HClO4
sulfuric acid
H2SO4
phosphoric acid
H3PO4
nitric acid
HNO3
CH3COOH = HC2H3O2
acetic acid
Salts
• Ionic compound composed of a cation
(positive ion) and an anion (negative
ion) from an acid
•
•
•
•
NaCl
CaSO4
NaHCO3
NaHSO3
Organic Compounds
• >11 million compounds
• Contain a C-C or C-H bond in
combination with
N, O, S, P or halogens
• Simplest = CH4
• Most complex = DNA
Hydrocarbons
• Only have carbon and hydrogen
• Simplest organic compounds
• From petroleum (crude oil)
Organic Compounds
Allotropes of carbon
Allotropes: Different forms of
an element in same
physical state
Catenation: ability of an
element to form chains
and/or rings of covalently
bonded atoms
Structural Formula
• Indicates the number and types of atoms
present in a molecule and also shows the
bonding arrangement of the atoms
• One possible isomer of C4H10
• Does not show 3D shape
Naming Organic Compounds
• Alkanes – saturated organic compound
– Contains only single bonds
– General Formula: CnH2n+2
• Alkenes – unsaturated organic compound
– Contains at least one double bond
– General Formula: CnH2n
• Alkynes – unsaturated organic compound
– Contains at least one triple bond
– General Formula: CnH2n-2
• What type of organic compound is C4H10 ?
Naming Hydrocarbons
1. Find the longest chain of carbon atoms. Choose the base
name that describes the number of carbon atoms in this
chain. Use the following endings:
Alkane (ane), Alkene (ene), Alkyne (yne)
# C atoms
Stem
# C atoms
Stem
1
meth
9
non
2
eth
10
dec
3
prop
11
undec
4
but
12
dodec
5
pent
13
tridec
6
hex
14
tetradec
7
hept
15
pentadec
8
oct
16
hexadec
Naming hydrocarbons
2. Number the carbon atoms in this longest chain
beginning at the end nearest the 1st branching.
•
If there is branching at equal distances from both ends
of the longest chain, begin numbering at the end
nearest the branch that is 1st in alphabetical order.
1
2
3
4
Naming Alkenes and Alkynes
• Number the carbon atoms in the chain
sequentially, beginning at the end nearer the
double or triple bond. If the parent chain has
more than 3 carbons, insert the number
describing the position of the double or triple
bond (indicated by its 1st carbon location)
before the base name.
1-butene
2-butene
Branches/Substituents on
the Main Chain
1) Additional Hydrocarbon branches
The hydrocarbon branches are called alkyl groups:
-CH3
methyl
-CH2CH2CH3
propyl
-CH2CH3
ethyl
-CH2CH2CH2CH3
butyl
2)The organic halides are elements from group 17
in the periodic table.
The prefix can be fluoro-, chloro-, bromo- or iodo-.
Hydrocarbon Branches or
Substituents
Assign the name (stem with yl ending) & position
number to each substituent or branch. Arrange
substituents in alphabetical order.
The hydrocarbon branches are called alkyl groups:
-CH3
methyl
-CH2CH2CH3
propyl
-CH2CH3
ethyl
-CH2CH2CH2CH3
butyl
Naming hydrocarbons
4. Use the appropriate prefix to group like
substituents: di = 2, tri = 3, tetra = 4, etc. Do not
use these prefixes when alphabetizing attached
groups
5. Write the name as a single word. Use hyphens to
separate numbers & letters and commas to
separate numbers. Do not leave any spaces.
Naming Alkenes and
Alkynes
In naming alkenes and alkynes, the mulitple
bond takes positional precedence over
substituents on the carbon chain. The double
bond is assigned the lowest possible number.
3,3-dimethyl-1-butene
4-methyl-2-pentene
Naming Organic Halides
(Alkyl Halides)
• The organic halides are named as halo- derivatives
of the parent hydrocarbon. The prefix can be
fluoro-, chloro-, bromo- or iodo-.
1-chloropropane
1-chloro-2-methylpropane
http://wps.prenhall.com/wps/media/objects/476/488316/index.html
Alkene Examples
3,4-dimethyl-3-hexene
3-ethyl-4,6-dimethyl-1-heptene
Naming Alkynes
• Named just like the alkenes except the
suffix –yne is added
ethyne
1-butyne
propyne
2-butyne
Alkyne Examples
3-methyl-1-butyne
5-methyl-2-hexyne
Arrangement of Atoms
• Isomers – compounds that have the same
molecular formula but different structures
Isomers of C6H14
• More C atoms in formula, more isomers
– 18 isomers for C8H18
– 35 isomers for C9H20
– 75 isomers for C10H22
Structural Isomers
• Isomers in which the atoms are bonded
together in different orders.
• C4H10 (note continuous chain of C atoms)
butane
methylpropane
Physical Properties of
Structural Isomers
Melting
Point (°C)
Boiling
Point (°C)
Density at
20°C
-138.4
-0.5
0.5788
-159.4
-11.633
0.549
Butane
Methylpropane
Ex #1) Butane, C4H10
ISOMERS
Ex #2) Butene, C4H8
Ex #3) 2-Butene, C4H8
Ex #4) methyl propene, C4H8
Functional Groups
an atom or group of atoms that is responsible for the
specific properties of an organic compound
Diffusion and Effusion
Diffusion: the mixing of molecules of 2 or
more gases due to their molecular motion
(spontaneous)
Effusion is the movement of gas atoms or
molecules through a small opening. Gases
confined in a container randomly pass
through a tiny opening in the container.
ex) hole in a tire; soda bottle (CO2 escaping)
Graham’s Law: The rate of effusion of a
gas is inversely proportional to the
square root of its molar mass.
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