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
13 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
• FeS2O3
• SnI4
MgH2
Ca(CH3COO)2
iron (II) thiosulfate
tin (IV) odide
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
2. Organic Acids
• 1st word: root formed from anion
Suffix ate changed to ic
• 2nd word: acid
C6H5COOH(aq)
or HC6H5COO(aq)
acetic acid
Benzoic acid
HCH3COO
or CH3COOH
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