Transcript C h e m i c a l F o r m u l a s

Binary Compound
A compound made
up of two parts,
a positive part and
a negative part
H2O
Binary Compound
The positive part is
always written first
H2O
Binary Compound
The negative part is
always written second
H2O
Binary Compound
Examples:
NH4OH
NaCl
H2SO4
Mg(OH)2
CO2
Chemical Formula
A shorthand method of
representing the makeup
of chemicals...
H2O
Chemical Formula
using chemical symbols
and oxidation numbers.
H2O
Chemical Formula
C6H12O6
Chemical Formula
(NH4)2SO4
Oxidation Number
The apparent charge
on an atom.
The charge on an ion.
Oxidation Number
Tells the number of
electrons gained or
lost when forming
compounds.
Oxidation Number
Atoms with positive
oxidation numbers
lose electrons.
+
Na
Oxidation Number
Metals commonly
have positive oxidation
numbers.
+
Na
Oxidation Number
Atoms with negative
oxidation numbers
gain electrons.
Cl
Oxidation Number
Nonmetals commonly
have negative oxidation
numbers.
Cl
Oxidation Number
The sum of the oxidation
numbers in a chemical
formula is equal to zero.
+
Na
Cl
Subscripts
Small numbers to the
lower right of a
chemical symbol.
H2O
Subscripts
Represent the number
of atoms of the element
in the compound.
H2O
Subscripts
Subscripts of 1 are
never used, they
are understood.
H2O
Subscripts
Multiply the subscript by
the oxidation number.
H2O
H 2O
Hydrogen:
Oxidation # X Subscript
+1
X 2
=
+2
H 2O
Oxygen:
Oxidation # X Subscript
-2 X 1
=
-2
H 2O
Total Oxidation Number:
(+2) + (-2) = 0
A Simplification
Make the oxidation of one
element the subscript
of the other element.
A Simplification
There is one possible problem!
+2 -2
CaO
Ca2O2
A Simplification
There is one possible problem!
+2 -2
CaO
Ca2O2
These subscripts will reduce...
A Simplification
Subscripts MUST be written
in their lowest form.
CaO
Example:
What is the formula of the
compound formed when
magnesium and chlorine
combine?
Example:
What is the formula of the
compound formed when
magnesium and chlorine
combine?
MgCl2
Example:
What is the formula of the
compound formed when
sulfur and potassium
combine?
Example:
What is the formula of the
compound formed when
sulfur and potassium
combine?
K 2S
Example:
What is the formula of the
compound formed when
oxygen and aluminum
combine?
Example:
What is the formula of the
compound formed when
oxygen and aluminum
combine?
Al2O3
Ion
An atom (or atoms)
with a charge.
Ion
Meaning the number of
protons and electrons
is no longer the same.
Ion
Chemists cannot change
an atom's protons,
so it must be the
electrons that change.
Ion
+
H
+2
Mg
This atom has -2
lost __ e- O
P
-3
Ion
This
atom
has
+
H gained __ e-
+2
Mg
O
P
-2
-3
Ion
+
H
+2
Mg
O
-2
This atom has
-3
lost __ eP
Ion
+
H
This atom has
+2
gained
__
e
Mg
O
P
-2
-3
Polyatomic Ion
A group of covalently
bonded atoms with an
overall charge.
Polyatomic Ion
NEVER change the
subscripts in a
polyatomic ion.
Polyatomic Ion
If more than one is
needed in a formula,
put parenthesis
around the ion...
Polyatomic Ion
and add the subscript
outside the parenthesis.
Polyatomic Ion
(NH4)2SO4
Example:
What is the formula of the
compound formed when
calcium combines with the
nitrate ion?
Example:
What is the formula of the
compound formed when
calcium combines with the
nitrate ion?
Ca(NO3)2
Example:
What is the formula of the
compound formed when
zinc combines with the
sulfate ion?
Example:
What is the formula of the
compound formed when
zinc combines with the
sulfate ion?
ZnSO4
Example:
What is the formula of the
compound formed when the
ammonium and phosphate
ions combine?
Example:
What is the formula of the
compound formed when the
ammonium and phosphate
ions combine?
(NH4)3PO4
Polyatomic Ion
The sum of the oxidation
numbers in a polyatomic
ion is equal to the
charge on the ion.
Polyatomic Ion
What is the formula
for the sulfate ion?
Polyatomic Ion
-2
SO4
The Sulfate Ion
Polyatomic Ion
-2
SO4
This oxidation number
must be positive.
Polyatomic Ion
-2
SO4
This oxidation number
must be negative.
Polyatomic Ion
-2
SO4
The total of the
oxidation numbers
must equal this charge.
Polyatomic Ion
-2
SO4
oxygen -2 X 4 = -8
+ sulfur
= ?
= -2
Polyatomic Ion
-2
SO4
oxygen -2 X 4 = -8
+ sulfur
=
+6
= -2
What is the formula for
the compound formed
when zinc combines
with the perchlorate ion?
Zn(ClO4)2
Zn(ClO4)2
What is the oxidation
number of chlorine in
this compound?
Zn(ClO4)2
Zn is +2 X 1 = +2
Zn(ClO4)2
Zn is +2 X 1 = +2
O is -2 X 4 X 2 = -16
Zn(ClO4)2
Zn is +2 X 1 = +2
O is -2 X 4 X 2 = -16
Cl's total must be +14
Zn(ClO4)2
Zn is +2 X 1 = +2
O is -2 X 4 X 2 = -16
Cl's total must be +14
There are 2 Cl's, each one = +7
Lab Question:
Does steel wool weigh more
or less after burning.
Quic kT ime™ and a
T IFF (Uncompress ed) decompress or
are needed to s ee this pi cture.
Combustion
A combustion reaction is defined
as a hydrocarbon combining with
oxygen to produce
carbon dioxide and water.
CH4 + 2O2
CO2 + 2H2O
Quic kT ime™ and a
T IFF (Uncompress ed) decompress or
are needed to s ee this pi cture.
Combustion
Metallic substances combine with
oxygen in oxidation-reduction
reactions, such as the rusting
of iron.
4Fe + 3O2
2Fe2O3
Quic kT ime™ and a
T IFF (Uncompress ed) decompress or
are needed to s ee this pi cture.
CH4 + 2O2
4Fe + 3O2
Combustion
CO2 + 2H2O
2Fe2O3
Do these two reactions suggest
that anything that burns is
actually combining with
oxygen in the atmosphere?
Quic kT ime™ and a
T IFF (Uncompress ed) decompress or
are needed to s ee this pi cture.
Combustion
Steel wool is commonly purchased
as pads formed from very thin
metal threads.
These pads are
used as abrasives.
QuickTi me™ and a
T IFF (Uncompressed) decompressor
are needed to see thi s pi cture.
coarse - medium - fine
Quic kT ime™ and a
T IFF (Uncompress ed) decompress or
are needed to s ee this pi cture.
Combustion
Is it possible that these
metal threads would burn?
QuickTi me™ and a
T IFF (Uncompressed) decompressor
are needed to see thi s pi cture.
coarse - medium - fine
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
An impressive pyrotechnic display
using steel wool.
Chemical Names
Naming
Binary
Compounds
Chemical Names
First:
Write the name
of the positive element.
Chemical Names
Then:
Write the name of the
negative element...
Chemical Names
with an ide ending.
Chemical Names
Examples:
NaCl
CaI2
Li4C
Chemical Names
Examples:
NaCl Sodium chloride
CaI2
Li4C
Chemical Names
Examples:
NaCl Sodium chloride
CaI2
Calcium iodide
Li4C
Chemical Names
Examples:
NaCl Sodium chloride
CaI2
Calcium iodide
Li4C
Lithium carbide
Chemical Names
Compounds
Containing
Polyatomic Ions
Chemical Names
First:
Write the name of the
positive element or ion.
Chemical Names
Then:
Write the name of the
negative part...
Chemical Names
Then:
If the negative part is a
polyatomic ion, write the
name with no changes...
Chemical Names
Then:
If the negative part is an
element, write the name
with an ide ending as
usual.
Chemical Names
Examples:
MgSO4
CaCO3
NH4Cl
Chemical Names
Examples:
MgSO4
CaCO3
NH4Cl
Magnesium sulfate
Chemical Names
Examples:
MgSO4
CaCO3
NH4Cl
Magnesium sulfate
Calcium carbonate
Chemical Names
Examples:
MgSO4
CaCO3
NH4Cl
Magnesium sulfate
Calcium carbonate
Ammonium chloride
Chemical Names
With
Roman Numerals
Chemical Names
If the positive element has
more than one possible
oxidation number...
Chemical Names
or if it is out of character,
its oxidation number
is shown...
Chemical Names
with a Roman numeral in
parenthesis after its name.
Chemical Names
Examples:
lead (IV) oxide
nitrogen (III) fluoride
copper (I) chloride
Chemical Names
Examples:
lead (IV) oxide
nitrogen (III) fluoride
copper (I) chloride
PbO2
Chemical Names
Examples:
lead (IV) oxide
nitrogen (III) fluoride
copper (I) chloride
PbO2
NF3
Chemical Names
Examples:
lead (IV) oxide
nitrogen (III) fluoride
copper (I) chloride
PbO2
NF3
CuCl
Chemical Names
The "Big 3" industrial acids:
Chemical Names
The "Big 3" industrial acids:
Chemical Names
The "Big 3" industrial acids: