Chemical Names & Formulas
7-1
Chemical formula…
• indicates the relative __________ and
____________ of atoms in a compound
• Covalent bonding: _____________ formula
– H2O 2 atoms H, 1 atom O
• Ionic bonding: ______________ ________
(simplest ratio of the cmpd’s pos. & neg. ions)
– MgCl2 1 Mg ion, 2 chloride ions
How many atoms of each
element are in Ba3(PO4)2 ?
Monatomic ions
• ions formed from ____________________
• page 205 Table 7-1 (know these…don’t
need to memorize, however!)
Naming monatomic ions
1. Cation: simply the name of the element
2. Anion: drop the ending and add –ide
•
•
NaCl: sodium chloride
Li2O: lithium oxide
•
NaF
______________________
•
AlN
_______________________
Binary Ionic Compounds
•
•
cmpds composed of 2 different elements
NaCl
• Rules for naming binary ionic cmpds:
1. Write the symbols side by side..cation first
2. Cross over the charges by using the abs.
value of each as the subscript for the other
3. Check…reduce to smallest whole-number
ratio, if necessary
Write and name the formulas for the
following binary ionic cmpds:
• lithium and iodine
• sulfur and magnesium
• zinc and bromine
• fluorine and calcium
• sodium and oxygen
Stock Nomenclature
• Roman numerals are used to indicate an
ion’s charge when it can form more than
one ion
• copper (I) chloride  Cu1+
• copper (II) chloride  Cu+2
Write the formula & name…
• copper (I) and oxygen
• iron (III) and sulfur
• copper (II) and chlorine
• tin (II) and chlorine
• tin (IV) and sulfur
• vanadium (II) and fluorine
• vanadium (III) and bromine
Polyatomic ions
• a “charged” group of atoms that are held
together by covalent bonds
• i.e.
SO42-
oxyanions
• negative ions that contain oxygen
•
•
•
•
-ate: most common form of group
-ite: one less O than common form
hypo: less O than the -ite form
per: more O than the -ate form
Examples of oxyanions
• Given: ClO31- is most common form
• ClO21_______________
• ClO1_______________
• ClO41_______________
Write the formula for the following:
• copper(II) nitrate
• potassium iodide
• magnesium hydroxide
• ammonium acetate
• calcium carbonate
• sodium sulfate
• iron(III) nitrate
Name the following:
• Ca(OH)2
• Fe(OH)2
• Na2SO4
• CuSO4
• FeO
• Fe2O3
Binary Molecular Compounds
• composed of ____ individually bonded
(covalent) units
• usually cmpds between 2 ______________
• 2 systems:
– newer: Stock system
– older: Prefix system (see p. 212….know
prefixes)
Numerical Prefixes
•
•
•
•
•
•
•
•
•
•
1
2
3
4
5
6
7
8
9
10
Rules for naming binary molecular cmpds:
1. Write the less electronegative element first. Precede
with a prefix only when there are >1 atoms of an
element.
2. Write the more electronegative element 2nd, utilizing
the –ide as in binary ionic cmpds. Always precede its
name with a prefix.
3. The “o” or “a” of the prefix is usually dropped when
the element’s name begins with a vowel.
•
•
•
•
IF3
iodine trifluoride
N2O5
dinitrogen pentoxide
Naming acids
• Ch 15 – learn about acids
• The term acid is used when a specific type of cmpd is in
a solution of water …. (aq) means aqueous solution
• Common oxyacids to know now:
• H2SO4 (aq)
sulfuric acid
• HNO3 (aq)
nitric acid
• H3PO4 (aq)
phosphoric acid
• H2CO3 (aq)
• __________________________
• CH3COOH (aq)
• __________________________
Naming acids
• -ate ion forms the –ic acid
– H2SO4 sulfuric acid
– HNO3 nitric acid
– H3PO4 phosphoric acid
• -ite ion forms the –ous acid
– H2SO3 sulfurous acid
– HNO23 nitrous acid
– H3PO3 phosphorous acid
Binary acids…
• HCl hydrochloric acid
• HF
________________________
• HBr
________________________
• HI
________________________
Sometimes all of the Hs don’t
come off of an acid when it
reacts……..
• H2CO3 carbonic acid
• HCO31- hydrogen carbonate
Diatomic elements:
•
•
•
•
•
•
•
H2
N2
O2
F2
Cl2
Br2
I2
Oxidation number
• also known as __________________ _________
• number assigned to an atom in a molecular cmpd
that indicates that general distribution of electrons
among the bonded atoms
• gives an insight into the combining ability of an
atom – not “real” charges but are artificial
“bookkeeping” devices to keep track of overall edistribution
• Ionic cmpds: the charge on the ion IS the electron
distribution ∴ ox. # = charge on ion…physically
meaningful info
Summary of Ox # Rules (p.216)
1. Pure elements have an ox. # of ____________
i.e. copper, Cu = ox # = ______
oxygen, O2 = ox # = ______
2. More electroneg. element has an ox. # = charge
it would have if it were an __________. Less
electroneg. element has an ox # = charge it
would have if it were a ____________.
i.e. oxygen in H2O O = ox # of ___________
3. F: _______ oxidation #
4. O: ________ oxidation # except in peroxide
(H2O2) where it is –1, and with halogens (OF2)
where it is +2.
5. H: ________ except when it’s more
________________. than other atoms
(metals….NaH) where it is ________.
6. Algebraic sum of all ox. #s in cmpd = ____.
7. Algebraic sum of all ox. #s in polyatomic ion =
___________________.
8. IF ionic, ox. # ______ charge of the ion
Assign oxidation numbers to each element in the
following cmpds or ions:
• CCl4
• NO2
• LiH
• sulfate ion
• nitrate ion
• H3PO4
• P4O10
Using the newer Stock system, write formulas
for the following molecular cmpds:
• nitrogen (II) oxide
• phosphorus (III) chloride
• sulfur (IV) oxide
• bromine
Formula Masses
• sum of the average atomic masses of all the atoms
represented in a formula
• (can be of a molecule, formula unit or ion)
•
•
•
•
•
Example: Formula mass of H2O:
2 (ave. atomic mass of H) + 1(ave. at. mass of O)
= 2(1.01 amu) + 1(16.00 amu)
= 2.02 amu + 16.00 amu
= 18.02 amu
Calculate the formula mass of the following:
• sulfuric acid
• calcium nitrate
• phosphate ion
• magnesium chloride
Molar Masses
• sum of the masses of the elements present in a mole of the
molecules or formula units that make up a compound
• Molar mass of water, H2O:
• 1 mole H2O = 2 mol H + 1 mol O
• 2 mol H x 1.01 g H =
2.02 g H
1 mol H
• 1 mol O x 16.00 g =
16.00 g O
1 mol O
+ _____________
•
18.02 g
• ∴ Molar mass of water = 18.02 g/mol
What is the molar mass of…
• aluminum sulfide
• sodium nitrate
• barium hydroxide
Using Molar Mass as a conversion
factor between “moles” ↔ “mass”
• What is the mass, in grams, of 0.500000 moles of
barium hydroxide?
• 0.500000 mol Ba(OH)2 x
• = 85.675 g Ba(OH)2
= 171.35
g Ba(OH)2
1 mole Ba(OH)2
How many moles are in 6.60 g of ammonium
sulfate?
Gram-Mole Conversions
Remember….
1 mole = 6.02 x 1023 “things”
• How many molecules are in 50.0 g of water?
• 50.0 g H2O x 1 mol H2O x
________g H2O
__ molecules
1 mol H2O
• = __________________ molecules H2O
Percentage Composition
• % = part x 100
whole
• percentage by mass of each element in a cmpd
Find the % copper in copper(I) sulfide
• % Cu = mass of Cu in 1 mole of Cu2S x 100%
mass of 1 mol of Cu2S
or… % Cu = mass of Cu in 1 mole of Cu2S x 100%
molar mass of Cu2S
• Cu2S = _____________ g/mol, and in1 mol Cu2S, there are
_______ mol Cu = ___________ g Cu
• % Cu = mass of Cu in 1 mole of Cu2S x 100%
mass of 1 mol of Cu2S
• = _________ g Cu
x 100% = ________% Cu in Cu2S
g Cu2S
What is the percent carbon in
ammonium carbonate?
Empirical formula
• formula that shows the smallest wholenumber ____________ ratio of the different
atoms in a compound
• In ionic cmpds, the formula unit usually is
the empirical formula
What is the empirical formula of
the following molecular formulas?
• Ethyne, C2H2
• Benzene, C6H6
• Glucose, C6H12O6
• Acetic Acid
Calculation of an empirical formula
• Empirical formula: smallest whole-number
MOLE ratio of the different atoms in a
compound
• ∴
• 1)determine moles of each element
• 2)determine the simples whole # ratio of
these moles
What would the formula be of a cmpd that
was composed of
2 mol hydrogen and 1 mol oxygen?
What would the formula be of a cmpd
composed of 0.78 mol Al & 2.34 mol Br?
What is the empirical formula for a
cmpd that contains 0.900 g calcium and
1.60 g chlorine?
Determine the empirical formula in a
cmpd that is 40.0% C, 6.71% H, and
53.3% O.
If the empirical formula is CH2 and the
molar mass is 42 g/mol, what is the
molecular formula?
If the molecular mass for the prev.
problem (cmpd that is 40.0% C,
6.71% H, and 53.3% O) is 90 g/mol,
determine the molecular formula.
Do Section Review p. 233
1.
2.
3.
4.
5.
Na2SO3
Fe2S3
K2CrO4
N2O5
N2O4