Naming Chemical Compounds
• Nomenclature-naming system
Naming Ionic Compounds
• Positive ions are first, then
negative ions
– Ex: sodium chloride NaCl
• The metal keeps it’s name
• The nonmetal gets a suffix of –ide
–
–
–
–
MgCl2
K3P
Al2O3
BeS
Stock SystemNaming
• Some metal elements can form two or more
cations with a different charge.
• The stock system denotes the specific ion by
putting the charge in ( ).
Examples:
– Iron (II) has a + 2 charge
– Iron (III) has a +3 charge
Possible Charges
Roman Numeral Charge
–
–
–
–
–
–
–
I
II
III
IV
V
VI
VII
–
–
–
–
–
–
–
+1
+2
+3
+4
+5
+6
+7
Practice
Write Names for the following:
• CuSO4
– Copper (II) Sulfate
• Fe2O3
– Iron (III) oxide
• ZnS
– Zinc (II) sulfide
• VCl4
– Vandium (IV) chloride
• Co(NO3)3
– Cobalt (III) Nitrite
• MnSO4
– Manganese (II) Sulfate
Practice
a)
b)
c)
d)
e)
f)
g)
Radium chloride
chromium(II)chloride
Aluminum phosphate
copper(I)sulfate
Magnesium sulfate
nitric acid
Sodium oxide
http://www.quia.com/jg/65800.html -
Compounds containing
Polyatomic ions
• Always put polyatomic ion in parentheses if
there are more than 1 of them
• Example: ammonium chloride
– NH4Cl
Practice
• Barium Nitrate
– Ba(NO3)2
• FeSO4
– iron (II) sulfate
Naming Molecular Compounds
• Use prefixes when naming simple molecular
compounds (memorize these)
1 = mono
2 = di
3 = tri
4 = tetra
5 = penta
6 = hexa
7 = hepta
8 = octa
9 = nona
10 = deca
• Naming Binary Molecular Compounds:
Compounds with 2 elements
– The least EN Atom goes first
• C,P,N,H,S,I,Br,Cl,O,F
– The first element is given a prefix if it contributes
more than one element to the molecule.
– The second element: Combine a prefix with the
root of that element with -ide at the end.
• Dioxide, pentoxide
• This is true for most molecules containing 2
elements
– The o or a at the end of a prefix is usually
dropped when the name of the element
begins with a vowel
Practice
1. CO
– Carbon Monoxide
2. CO2
– Carbon Dioxide
3. CCl4
– Carbon TetraChloride
4. SiF4– Silicon Tetraflouride
5. Nitrogen Monoxide
– NO
6. N2O3
– Dinitrogen Trioxide
7. Phosphorus Trichloride
– PCl3
Using Chemical Formulas
• Subscript indicates how many moles of that atom or
polyatomic ion are in 1 mole of that compound.
•
•
•
•
KNO3
Na2SO4
Ca(OH)2
(NH4)2SO3
Using Chemical Formulas
• Formula mass-sum of all the average atomic
masses of all elements in compound.
• Ex: H2SO4
• 2 Hydrogen 2 x 1.01 = 2.02
• 1 Sulfur
1 x 32.07 =32.07
• 4 Oxygen
4 x 16.00 =64.00
total = 98.09
OR
• EX: NaCl
• 1 sodium ion
• 1 Chloride ion
22.99
35.45
total= 58.44
Practice
• (NH4)3(PO4)
• Al2O3
• Na2O
Molar Mass as a Conversion Factor
• Converting between moles and
grams with compounds.
– 1st calculate formula mass of given
compound. (unit gram/mole)
– 2nd convert either by multiplying or
dividing by the formula mass
• molesgrams (x) by formula mass
• Gramsmoles (divide) formula mass
Practice
• What is the mass of 4.5 moles
of Ca(CO3)?
– 4.5 x 102 g Ca(CO3)
• What is the mass of 2.0 moles
of Na(NO3)?
– 1.7 x 102 g Na(NO3)
• How many moles are
contained in 25.0 grams of
AgCl?
– .174 mol AgCl
• How many moles are
contained in 5.0 grams of
ZnCl2?
– .037 mol ZnCl2
Percent Composition
• Gives the percent by molar mass of each
element in a compound.
• 1st calculate the total molar mass of the
compound
• H2SO4
2 H x 1.01 = 2.02
1 S x 32.07 = 32.07
4 O x 16.00 = 64.00
98.09
continued
• 2nd Divide each individual atoms
mass by the total mass.
• 3rd Multiply each by 100 (or move
decimal two places to the right)
2 H x 1.01 = 2.01/98.16 = 0.0205 =2.05%
1 S x 32.07 = 32.07/98.16 = 0.327 =32.7%
4 O x 16.00 = 64.00/98.16 = 0.652 =65.2%
Check to make sure % adds to 100
(or close to 100)
• More Practice Pg 244 Practice
Problems
• ZnSO4•7H2O
– 42.85%
Determining Chemical Formulas
• Empirical formula-symbols of elements in
compound showing the smallest whole
number ratio.
• Convert percents of elements in a
compound into formula.
How to:
•
•
•
•
1st change % to grams
2nd convert grams to moles
3rd divide each by the least
Ex: Determine the formula
of a compound made up
of the following percents:
32.38 % Na
22.65 % S
44.99 % O
Practice problems 1-3 p.247
Molecular formulas
• Actual formula of a
molecular compound
• C2H4 simplifies to CH2
• C3H6 simplifies to CH2
• C2H4 (ethene) and C3H6
(cyclopropane)
How the empirical formula relates
to the molecular formula:
•
•
•
•
•
•
EF = empirical formula
MF = molecular formula
X( EF) = (MF)
1st solve for x
X= (MF)/(EF)
HINT-BIG NUMBER ALWAYS
GOES ON TOP
• Multiply (EF) by x to get the
molecular formula
Example
• The empirical formula of a
cpd of phosphorus and
oxygen was found to be
P2O5. the molar mass of
this cpd is 283.89g/mol.
What is the cpd’s
molecular formula?
Practice Problems 1-2 p. 249
Give the formula for the
following:
•
•
•
•
•
•
•
•
•
•
1. potassium oxide
2. lithium phosphide
3. aluminum chloride
4. calcium bromide
5. iron(II)oxide
6. iron(III)oxide
7. tin(IV)fluoride
8. copper(II)chloride
9. lead (II) sulfide
10. magnesium chloride
Determine the molecular
formula:
• 1. Emperical formual = CH,
molar mass = 78 g/mole
• 2. Emperical formula =
NO2, molar mass = 92.02
g/mol
• 3. Mesitylene has an
empirical formula of C3H4.
What is the molecular
formula(mass 121)?