Naming Compounds
Writing Formulas
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There are more than 50 million named
chemical substances
Many have common names that we use
everyday like sugar, table salt, borax, and
sand
They all have systematic names that make
keep track of them easier and uniquely
identify each one.
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Follow the Law of Definite Proportion.
Have a constant composition.
Same formula (atoms) every time
Two Major Types of Compounds
 Ionic
 Covalent or Molecular
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Covalent Compounds
Made of molecules
Made by joining nonmetal atoms together
into molecules
Non-Metal Non-Metal Combinations
Soft solids, liquids, and gases
Carbon dioxide
CO2
Dihydrogen monoxide H2O
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Made of cations and anions
Positive ion bonded to negative ion
Metal Non-Metal Combinations
The electrons lost by the cation are gained by
the anion
The cations and anions surround each other
Smallest ratio of ions in an ionic compound is
a FORMULA UNIT.
All hard, brittle solids
Calcium chloride CaCl2
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Positive ions
Formed by losing electrons
More protons than electrons
Metals usually
+1
K
+2
Ca
Has lost one electron
Has lost two electrons
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A negative ion
Has gained electrons
Non metals
Charge is written as a superscript on the
right.
-1
F
-2
O
Has gained one electron
Has gained two electrons
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Shows the kind and number of atoms in the
smallest piece/ratio of a substance
CO2
C6H12O6
 AlBr3
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The smallest whole number ratio of atoms in
an ionic compound.
Ions surround each other so you can’t say
which is hooked to which
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The Stock (Roman numeral) System used for
Ionic Compounds
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The Numerical Prefix System used for
Covalent Compounds
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Write the name of the less electronegative
element or polyatomic ion
Write down the name of the other element or
polyatomic ion
Put a Roman numeral in parentheses after
the first element name
 The Roman numeral is equal to the oxidation
state (charge) of the first element
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Composed of 2 different elements
Write down the name of the less
electronegative element (metal)
Write down the root of the other element
then add ---ide to the end.
Place the roman numeral in parentheses after
the first element if needed
 Roman # equals the charge of the first element
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For Elements in Groups 1, 2,13-18 on the
Periodic Table you can tell what kind of ion
they will form from their location on the table
Elements in the same group have similar
properties
Including the charge when they are ions
+1
+2
+3
-3 -2 -1
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We have to figure those out some other way.
More on this later.
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We will use the systematic way
Cation- if the charge is always the same just
write the name of the metal (Gr. 1, 2, 13)
Transition metals can have more than one
type of charge
Indicate the charge with a Roman numeral in
parentheses
How we determine this in a bit
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Na+1
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Ca+2
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Al+3
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Fe+3
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Fe+2
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Pb+2
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Li+1
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Potassium ion
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Magnesium ion
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Copper (II) ion
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Chromium (VI) ion
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Barium ion
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Mercury (II) ion
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Anions are always the same when it comes to
charge
Change the element ending to – ide
F-1 fluoride
S-2 sulfide
P-3 phosphide
Te-2 telluride
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Cl-1
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N-3
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Br-1
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O-2
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Ga+3
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Sulfide ion
iodide ion
phosphide ion
Strontium ion
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Groups of atoms that stay together and
have a charge
You must memorize these or use an ion
sheet
Acetate C2H3O2-1
Nitrate NO3-1
Nitrite NO2-1
Hydroxide OH-1
Permanganate MnO4-1
Cyanide CN-1
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Sulfate SO4-2
Sulfite SO3-2
Carbonate CO3-2
Chromate CrO4-2
Dichromate Cr2O7-2
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Phosphate PO4-3
Phosphite PO3-3
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Ammonium NH4+1
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Ending
Formula
Name (from
the element
that is not
oxygen)
Chlorine
Formula
---ide
No oxygen S-2
Sulfide
Chloride
Cl-1
---ite
Some
oxygen
SO3-2
Sulfite
Chlorite
ClO2-1
---ate
More
oxygen
SO4-2
Sulfate
Chlorate
ClO3-1
---
Less
oxygen
Hypochlorite
ClO-1
Per--- -----ic
Most
oxygen
Perchlorate
ClO4-1
Hypo--ite
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Binary Compounds
 2 elements
 Metal nonmetal
 a cation and an anion
 +-
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To write the names just name the two ions.
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Easy with Representative elements
 Groups 1, 2, 13
 Charge determined by location in table
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NaCl = Na+ Cl- = sodium chloride
MgBr2 = Mg+2 Br- = magnesium bromide
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The problem comes with the transition
metals and in other variable charged cations
Elements not are not in groups 1, 2 , or 13.
Need to figure out their charges.
How?
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The compound must be neutral
Same number of + and – charges
Look up the charge on the negative
Calculate the total negative charge
Must be equal to total positive charge
Divide positive total by number of atoms
Result is equal to charge on positive
This is the Roman numeral
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Write the name of CuO
Copper is not in gr 1, 2, or 13 so need a roman
numeral
O is -2 therefore
Copper must be +2 so the roman numeral = 2
Name is Copper (II) chloride
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Name the following:
CoCl3
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Write the name of Cu2S
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Fe2O3
Write the names of the following
 KCl
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Na3N
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CrN
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Sc3P2
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PbO
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PbO2
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Na2Se
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Will have at least one polyatomic ions
At least three elements
Name the ions: Use a roman numeral if needed.
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NaNO3
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CaSO4
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CuSO3
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(NH4)2O
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LiCN
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Fe(OH)3
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(NH4)2CO3
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NiPO4
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Things to remember:
 The charges in a compound have to add up to zero
1.
2.
3.
Write down each ion with charges
Make the charges equal by adding
subscripts
Put polyatomic ions in parentheses before
using a subscript
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Write the formula for calcium chloride.
Calcium is Ca+2
Chloride is Cl-1
Charge on compound must be 0.
 So 2 Cl-1 are needed to make the charge =
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to zero.
 CaCl2
 2 atoms of chlorine for every one atom of calcium
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Aluminum nitrate
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Lithium sulfide
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tin (II) oxide
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tin (IV) oxide
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Magnesium fluoride
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Copper (II) sulfate
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Iron (III) phosphide
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gallium nitrate
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Iron (III) sulfide
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Ammonium chloride
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ammonium sulfide
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barium nitrate
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If cation has a (Roman Numeral), the number
is the charge of the positive ion
If anions end in -ide they are probably off the
periodic table (monoatomic) but can be
cyanide, hydroxide
If anion ends in -ate or -ite it is polyatomic
Writing names and Formulas
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Nonmetal Nonmetal combinations
smallest piece is a molecule
Also called covalent compounds
not held together because of opposite
charges
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Molecular compounds name tells you the
number of atoms
Uses prefixes to tell you the number
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1 mono2 di3 tri4 tetra5 penta6 hexa7 hepta8 octa-
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9 nona10 deca-
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9 nona10 decaTo write the name write two words
Prefix name Prefix name -ide
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9 nona10 decaTo write the name write two words
Prefix name Prefix name -ide
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One exception is we don’t write mono- if
there is only one of the first element.
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9 nona10 decaTo write the name write two words
Prefix name Prefix name -ide
One exception is we don’t write mono- if
there is only one of the first element.
No double vowels when writing names (oa
oo) except with i
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N2O
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NO2
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Cl2O7
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CBr4
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CO2
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BaCl2
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diphosphorus pentoxide
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tetraiodide nonoxide
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sulfur hexaflouride
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nitrogen trioxide
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carbon tetrahydride
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phosphorus trifluoride
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aluminum chloride
Writing names and Formulas
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Compounds that give off hydrogen ions when
dissolved in water.
Must have H in them
will always be some H next to an anion
HCl
H2SO4
The anion determines the name
Anion
Example
Acid
Example
….ide
Cl- 1
chloride
Hydro…ic
HCl
Hydrochloric acid
…..ite
ClO2- 1
chlorite
….ous
HClO2
Chlorous acid
Hypo…..ite
ClO-1
hypochlorite
Hypo….ous
HClO
Hypochlorous acid
…..ate
ClO3- 1
chlorate
….ic
HClO3
Chloric acid
Per…ate
ClO4- 1
perchlorate
Per……ic
HClO4
Perchloric acid
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Rule 1: If the anion attached to hydrogen is
ends in -ide, put the prefix hydro- and change
-ide to -ic acid
 Example: HCl - hydrogen ion and chloride ion
 Example: H2S hydrogen ion and sulfide ion
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If the anion has oxygen in it
 it ends in -ate of -ite
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Rule 2: change the suffix -ate to -ic acid
Example: HNO3
 Hydrogen and nitrate ions
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Rule 3: change the suffix -ite to -ous acid
 Example: HNO2 Hydrogen and nitrite ions
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HF
H3 P
H2SO4
H2SO3
HCN
H2CrO4
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Hydrogen will always be first
name will tell you the anion
make the charges cancel out.
Rule 1: hydro- no oxygen,
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Rule 2 : no hydro, -ate comes from -ic,
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Rule 3: no hydro -ite comes from -ous
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-ide ion
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hydroiodic acid
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acetic acid
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carbonic acid
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phosphorous acid
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hydrobromic acid
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A solid compound with a specific number of
water molecules bonded to it
Release water when heated at fairly low
temperatures
Anhydrous Solid•xH2O)
Common Example: CuSO4 5H2O
Copper (II) sulfate pentahydrate
The penta indicates five water molecules for
each copper (II) sulphate particle
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The prefix indicates the
number of water
molecules bonded to
the anhydrous salt
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zinc sulphate heptahydrate
copper (I) sulphite monohydrate
cobalt (II) fluoride tetrahydrate
lithium nitrate trihydrate
sodium sulphate decahydrate
calcium nitrate trihydrate
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Na2SO4 10H2O
LiNO3 3H20
Cu2SO3 3H20
Ca(N03) 2 2H20
MgS04 7H20
ZnS04 7 H20