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Elements  compounds
◦ New properties are created
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Why do elements form compounds?
To become more chemically stable by getting
a complete outer energy level and lowering
potential energy.
What are chemical formulas?
 A formula that tells you number of
atoms each element in a compound
represented by symbols and
subscripts
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Subscripts
◦ small numbers to the lower right of
the chemical symbol
◦ Represents the number of atoms of that
element present in the compound
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***the subscript of 1 is never written
in a chemical formula; it is understood
since the chemical symbol is there****
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Looking at the
following
formulas state
the number of
atoms for each
compound.
NH4OH
 NH4C
 Ag2O
 2 K2SO4
 Ca (NO3)2
 3 Na2S
 2 Al2(SO4)3
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Between metals
and nonmetals
 Cations and
anions
 Transferring
electrons
Between
nonmetals and
nonmetals
 Sharing electrons
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Ionic compounds
Covalent Compounds
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What are characteristics of monatomic
ions?
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Ions formed from a single atom
Cations and anions
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What are binary ionic compounds?
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Compounds composed of two
elements
Total number of positive and negative
charges must be equal
What are characteristics of polyatomic
ions?
 Form ternary compounds (3 elements)
 Covalent molecules with a charge
 Behave as if they were one atomic ion
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Ammonium – NH41+
(only positive one)
Hydroxide – OH1Nitrite – NO2 1Nitrate – NO3 1Sulfite – SO3 2Sulfate – SO4 2-
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Carbonate – CO3 2Bicarbonate –
HCO3Phosphate - PO4 3Chlorate – ClO3Chlorite – ClO2Cyanide – CNAcetate – C2H3O2-
Remember, oxidation numbers tell
how many electrons an atom has
gained, lost, or shared to become
stable.
 Shown as superscripts.
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Main group elements the oxidation number is
set. The transition elements and those of
group 14 vary.
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We use oxidation numbers and their
least common multiples to write
formulas
So, if both subscripts are divisible by the
same number, they must be reduced to
have formula in proper form.
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When writing formulas, the compound
should be neutral (same number of +
and - charges)
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Type I compounds – ionic compounds made
from main group 1, 2, 13 metals and
nonmetals of groups 15, 16, 17
Type II compounds – ionic compounds made
from transition metal and nonmetal; named
by using stock system (using Roman
Numerals)
Type III compounds – covalent compounds
composed of 2 non-metals; named using
prefixes
TYPE I COMPOUNDS
 Write cation (metal) name first
 Then, write the nonmetal name. Drop
the ending and add –ide to the end
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Ex. Nitride, sulfide, fluoride, oxide,
bromide, iodide, chloride, telluride,
phosphide
If it is a ternary compound (with a polyatomic
ion)
First write name of cation
Then write name of polyatomic ion
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TYPE II COMPOUNDS (named using stock
system)
If it is a transition metal, name the cation first, then
put a Roman Numeral after its name to represent
its oxidation number!!!
◦ Look at the subscript of the nonmetal for this
information!!!
Then name the anion. Remember to drop the
ending and add –ide or if it is polyatomic name the
polyatomic ion.
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Practice Naming Ionic Compounds
MnO2
Ca (NO3)2
BaSO4
Cu3P2
AgCl
B2O3
MgCl2
Ba (OH)2
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Practice Naming Ionic Compounds-Answers
MnO2 – Manganese (IV) oxide
Ca (NO3)2 – Calcium nitrate
BaSO4 – Barium sulfate
Cu3P2 – Copper (II) phosphide
AgCl – Silver (I) chloride
B2O3 – Boron oxide
MgCl2 – Magnesium chloride
Ba (OH)2 – Barium hydroxide
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Bell Work 01/22/13
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Name the following ionic compounds
Be (OH)2
 Mn (NO3)3
 FePO4
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Bell Work 01/22/13
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Name the following ionic compounds
Be (OH)2 – Beryllium hydroxide
 Mn (NO3)3 – Manganese (III) nitrate
 FePO4 – Iron (III) phosphate
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1.
2.
3.
4.
5.
Write the ions beside each other (first
cation then anion)
Write the oxidation of each as
superscripts w/ charge
Drop the +/- signs
Crisscross superscripts so they
become subscripts
Reduce when possible
Practice
Write the formula for the following
TYPE I compounds
 Magnesium chloride
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Potassium iodide
Practice-Answers
 Magnesium chloride- MgCl2
 Potassium iodide- KI
Practice on your own
Write the formula for the following
Type I compounds
Boron oxide
 Beryllium and Nitrogen
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Practice-Answers
 Boron oxide- B2O3
 Beryllium and Nitrogen – Be3N2
Write the formula unit for the following
type I compounds:
Lithium nitride
Sodium fluoride
Bell Work 1/15/13
Write the formula unit for the following:
Lithium nitride – Li3N
Sodium fluoride - NaF
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How do you write the formula of an ionic compound
with a transition metal? Written as Roman Numerals
Ti (4+, 3+)
Cr (2+, 3+, 6+)
Mn ( 3+, 4+, 6+)
Fe (2+, 3+)
Co (2+, 3+)
Ni (2+, 3+)
Cu (2+, 1+)
Ag (1+)
Zn (1+, 2+)
Pb (2+, 4+)
Sn (1+, 2+, 4+)
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When it is a transition metal (type II
compound).
First, write the symbol of the cation. Use the
roman numeral for the oxidation number.
Then, write the symbol for the anion and use
periodic table to determine its oxidation
number.
Criss-cross oxidation numbers.
Reduce if necessary.
Practice
Write formula for the following
Iron (III) oxide
 Zinc (II) chloride
 Silver (I) chloride
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Practice
Write formula for the following
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Iron (III) oxide – Fe2 O3
 Zinc (II) chloride – Zn Cl2
 Silver (I) chloride – Ag Cl
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Practice
Write formula for the following
Copper (II) phosphide
 Manganese (IV) oxide
 Lead (IV) sulfide
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Practice
Write formula for the following
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Copper (II) phosphide – Cu3 P2
 Manganese (IV) oxide – Mn O2
 Lead (IV) sulfide – Pb S2
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How do you write the formula of an ionic
compound with a polyatomic ion?
 Treat the polyatomic ion as one
 Use parenthesis around polyatomic ion
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Crisscross oxidation numbers to determine
formula
Only reduce subscripts that are outside
of the parenthesis
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Cation
 Ca 2+
 Mg 2+
 Ba 2+
 Ba 2+
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Anion
 NO 3 –
 PO 4 3 OH –
 SO 4 2-
Bell Work 1/23/13
Practice writing formulas with polyatomic
ions
Sodium carbonate
Calcium carbonate
Aluminum carbonate
Sodium phosphate
Calcium phosphate
Aluminum phosphate
Practice writing formulas with polyatomic
ions
Sodium carbonate – Na2CO3
Calcium carbonate – CaCO3
Aluminum carbonate – Al2(CO3)3
Sodium phosphate – Na3 PO4
Calcium phosphate – Ca3 (PO3)2
Aluminum phosphate – AlPO3
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Between nonmetals and nonmetals
Type III Compounds that does not contain
cations and anions
You do NOT crisscross to determine formula
Look at the name, it tells you the formula!!!!
You MUST KNOW AND USE prefixes (it tells
the number of atoms of the element in the
compound)
DO NOT REDUCE FORMULAS!!!
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1.
2.
3.
4.
5.
Prefixes
MonoDiTriTetraPenta-
Hexa7. Hepta8. Octa9. Nona10. Deca6.
RULE!!!! Do NOT use “mono” on the
first element!
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Practice writing covalent compound
formulas
 Dinitrogen
trioxide
 Carbon tetrahydride
 Phosphorous pentoxide
 Disulfur trifluoride
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Practice writing covalent compound
formulas - Answers
 Dinitrogen
trioxide – N2O3
 Carbon tetrahydride – CH4
 Phosphorous pentoxide – PO5
 Disulfur trifluoride – S2F3
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First, use the nonmetal furthest to the left on
the periodic table. If they are in the same
group, write the element with the larger
period number first. Write Prefix and name of
element. DO NOT USE MONO!!!
Then, write the second nonmetal with prefix,
root, ending in –ide.
Look at subscript to determine the prefix
needed
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Bell work 01/30/13
Name the following covalent compound!
 PCl3
 NH3
Practice naming covalent compounds
PCl3 – Phosphorous trichloride
NH3 – nitrogen trihydride
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Practice naming covalent compounds on
worksheet
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Compounds with or without water
hydrates (compounds with water)
Name ionic compound as usual; but, water is
covalent compound so must use prefixes
Ex. CaSO4 · 2 H2O
◦ Calcium sulfate dihydrate
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Anhydrous (without water)
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Binary Acid
H + element
Hydro
ic acid
H+F
Hydrofluoric acid
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H + Polyatomic acid (“oxo” acids)
DO NOT START WITH HYDROate  ic
“I ate something ic-ky”
Nitrate  nitric acid
HNO3
ite  ous
“I took a b-ite of something delicious”
Nitrite  nitrous acid
HNO2
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Naming Bases
Name the metal CATION first; it keeps its
name as listed in the Periodic Table.
The polyatomic ion "hydroxide" (-OH) also
keeps its name.
Examples:
LiOH is "lithium hydroxide"
Ca(OH)2 is "calcium hydroxide"
NH4OH is "ammonium hydroxide"