Transcript Nomenclature PPt - My Teacher Pages

Chemical Formulas,
and
Nomenclature
Names of Elements
• The most common source for element
names is a property of the elements.
EX: nitrogen: Greek for nitron (niter) and
genes (to be born). Niter was the name for
any naturally occurring substance that
contained nitrogen.
• Some elements get their name from their
place of discovery, person of honor, or
from the mineral from which they are
obtained.
Chemical Symbols
• Chemical symbols of the elements are
shorthand representations of the elements.
• J. J. Berzelius, a Swedish chemist, is
generally given credit for creating the
modern symbols for the elements.
• Symbols correspond to the first letter of the
name, or the first two letters if needed to
distinguish between elements with the
same first letter.
Chemical Symbols
• In some cases, the Latin form of the
element was used.
EX:
Iron is Fe for ferric
Chemical Formulas
• A chemical formula is a combination of
symbols that represents the composition of
a compound.
• Chemical symbols are used to indicate
types of elements present.
• Subscripts are used to indicate the number
of atoms for each element present.
chemical symbols
C8H18
number of atoms of each element
• 8 atoms of carbon
• 18 atoms of hydrogen
Oxidation Numbers of
Monatomic Ions
• Because atoms want to reach an octet of
valence electrons, the oxidation numbers,
positive or negative charges, can be
predicted for single atoms (monatomic).
• Metals tend to have positive oxidation
numbers. (lose e-)
• Nonmetals tend to have negative
oxidations numbers. (gain e-)
0
1+
2+
3+ 4+ 3- 2- 1-
most 2+,
but varies
Oxidation Numbers of
Polyatomic Ions
• Polyatomic ions are ions that are made up
of two or more atoms.
• Refer to table of Polyatomic ions.
• Polyatomic ions generally have the
following endings: “ate” or “ite”
EX:
NO2- nitrite
PO4-3 phosphate
Polyatomic Ions
Oxidation Numbers
• The sum of the oxidation numbers in a
compound must equal zero.
EX: CaCl2 = Ca+2 + Cl- + Cl2 positive charges –
2 negative charges = 0
• The charge on a monatomic ion is its
oxidation number.
EX: Ba+2 has an oxidation of +2
Cl- has an oxidation of -1
Oxidation Numbers of
Transition Elements
•
The oxidation number of a transition
element can be determined by two
methods.
1. The suffix ending (old system):
EX: ferrous is Fe+2
ferric is Fe+3
2. The Roman numeral indicating oxidation.
EX: iron (II) is Fe+2
iron (III) is Fe+3
Writing Ionic Formulas
• Remember:
• Ionic compounds are composed of metals
and nonmetals.
• Ionic compounds are made from the
gaining or losing of electrons and the
resulting electrostatic force that holds the
ions together.
• The sum of the oxidation numbers in a
compound must equal zero.
Writing Ionic Formulas
• When writing formulas, the cation (metal
ion) is always written before the anion
(nonmetal ion).
• When using polyatomic ions, refer to
charge.
There is only one polyatomic cation:
NH4+ that we will focus on.
The remaining are polyatomic anions.
Writing Ionic Formulas
• You can determine the formulas of ionic
compounds when given the only the name.
EX:
Sodium chloride
Elements:
sodium and chlorine
Oxidation:
+1
-1
# of each needed
for 0 oxidation:
1
1
Formula:
NaCl
Writing Ionic Formulas
EX:
Elements:
Oxidation:
# of each needed
for 0 oxidation:
Formula:
Magnesium Iodide
magnesium and iodine
+2
-1
1
2
(+2 + -1 + -1)
MgI2
Writing Ionic Formulas
• Now, let’s include polyatomic ions.
EX:
Sodium hydroxide
Elements:
Na and OH
Oxidation:
+1
-1
# of each needed
For 0 oxidation:
1
1
Formula:
NaOH
Writing Ionic Formulas
EX:
Elements:
Oxidation:
# of each needed
For 0 oxidation:
Formula:
Aluminum sulfate
Al and SO4
+3
-2
2
3
(+3 + +3 + -2 + -2 + -2)
+6 + -6 = 0
Al2(SO4)3
Criss Cross Method of Writing
Formulas
• Notice a trend between the
oxidation/charges of ions and the
subscripts of elements.
EX: Mg+2 and Cl- gives
MgCl2
EX:
Al+3 and SO4-2 gives
Al2(SO4)3
Criss Cross Method of Writing
Formulas
• This method crosses charges and subscripts
to form neutral compounds.
Al +3 and O-2
Al
and O
Al2O3
(neutral)
Criss Cross Method of Writing
Formulas
EX:
Lead (II) phosphate
Pb+2 and PO4 -3
Pb
and PO4
Pb3(PO4)2
Checking Criss Cross
• You can check to make sure your work is
correct by finding the Least Common
Multiple (LCM), and calculating charges.
EX:
Pb+2 and PO4 -3
LCM is: 6
Pb: 6 ÷ 2 (charge) = 3
PO4: 6 ÷ 3 (charge) = 2
• Ionic compounds need to be in the lowest
whole number ratio.
• EX: Pb2(CrO4)4  Pb(CrO4)2
• Exceptions:
1. peroxides: Na2O2, Ag2O2
2. Mercury(I), Mercurous: Needs an overall
+2 oxidation to be stable.
EX: Hg2(NO3)2, Hg2Cl2
Nomenclature
• Nomenclature is defined as a naming
system.
• Chemistry uses nomenclature to
standardize names of chemicals.
• Let’s take a look.
Naming Binary Ionic
Compounds
A. Naming binary (composed of two) ionic
compounds.
1. Name of cation is given first. The
name of the cation is the same as the
element.
2. Name of anion is given last. The name
of the anion is the same as the element,
but with an “ide” suffix.
Naming Ionic Compounds
EX:
Al2O3
Aluminum and Oxygen
Aluminum oxide
cation
anion
Naming Ionic Compounds
EX: AgCl is __________________
Silver chloride
ZnO is ___________________
Zinc oxide
CaBr2 is ___________________
Calcium bromide
Na2O is ___________________
Sodium oxide
Naming Ternary Ionic
Compounds
B. Compounds containing a polyatomic ion.
1. Cation rule from binary applies.
2. Anion takes the name of the
polyatomic ion as found on the table.
EX:
Al2(SO4)3
Aluminum sulfate
EX:
Mg(OH)2
Magnesium hydroxide
Naming Ionic Compounds
EX: Li2CO3 is ____________________
Lithium carbonate
Ba(OH)2 is ___________________
Barium hydroxide
Zn(NO3)2 is __________________
Zinc nitrate
KClO3 is ___________________
Potassium chlorate
Naming Transition Element
Compounds
• Cation rule applies to transition metals but
must also include oxidation state for those
transition elements that have more than one
oxidation.
• Common elements with more than one
oxidation:
Fe, Cu, Mn, Pb, Co, Hg, Sn
New System
• The most common system for naming
metals with more than one oxidation is the
Roman Numeral system.
• In this system, the oxidation is shown by
writing it in parenthesis after the metal
name.
EX: Pb+2 = Lead(II)
Sn+4 = Tin(IV)
Cu+1 = Copper(I)
Classic System
• The classic system of naming metals with
more than one oxidation uses Latin (or
Greek) root name of element and suffixes
to show oxidation.
• “ous” is used for the lesser oxidation.
• “ic” is used for the greater oxidation.
EX: Pb+2 = Plumbous
Sn+4 = Stannic
Cu+1 = Cuprous
Classic System Root Names
•
•
•
•
Iron
Copper
Tin
Lead
Fe
Cu
Sn
Pb
Ferrous
Cuprous
Stannous
Plumbous
Ferric
Cupric
Stannic
Plumbic
• There are transition elements that will
retain the element name as found on the
periodic table combined with a suffix.
EX: Mercury
Hg Mercurous
Mercuric
Cobalt
Co Cobaltous
Cobaltic
Manganese
Mn Manganous
Manganic
• How to determine the charge of the metal in
an ionic compound:
-Refer to the anion and determine overall
negative charge.
-Metal cation must contribute same positive
charge.
EX: Fe2O3
1. Oxygen is -2 x the 3 atoms = -6 overall.
2. 2 iron atoms at an oxidation of +3 will
result in +6 overall.
3. The oxidation of Fe is +3
Transition Metals with One
Oxidation
• We only use the Roman Numeral or
Classic System only for those metals with
more than one oxidation.
• Transition elements with only one possible
oxidation will be named with the name of
the metal only. (like Group 1, 2, and 13)
Zinc (can only be +2)
Silver (+1)
Cadmium (+2)
•
1.
2.
3.
4.
5.
6.
7.
8.
9.
Name each compound using the Roman
Numeral System and the Classic System
FeO
Sn(NO3)4
CuCl
MnSO4
HgBr
HgCl2
CoCO3
Pb(ClO4)4
CuSO3
Naming
• Name the following compound:
• Ba(Na)2
Banana
Naming Binary Molecular
Compounds
• Unlike ionic compounds, molecular
compounds are composed of individual
covalently bonded units, or molecules.
• Prefixes are used to indicate number of
each type of element in the compound.
• Write the prefixes as indicated on the next
slide.
Molecular Prefixes
1
mono-
6
hexa-
2
di-
7
hepta-
3
tri-
8
octa-
4
tetra-
9
nona-
5
penta-
10
deca-
Naming Binary Molecular
Compounds
Follow these rules:
1. The less electronegative element is given
first. It is given a prefix if it contributes
more than one atom to the molecule.
Naming Binary Molecular
Compounds
2. The second element is named by
combining (a) a prefix indicating the
number of atoms contributed by the
element, (b) the root of the name of the
second element, and, (c) the ending -ide.
3. The o or a at the end of a prefix is usually
dropped when the word following the
prefix begins with another vowel.
EX: monoxide or pentoxide
Naming Binary Molecular
Compounds
EX:
P4O10
1. P is less e-neg and it has more than one
atom in this molecule.
Tetraphosphorus
2. O is named by combining prefix, root
name, and ide ending.
decoxide (a is dropped from prefix)
*combine to form: Tetraphosphorus decoxide
Naming Binary Molecular
Compounds
EX: SO3 is ____________________
Sulfur trioxide
PBr5 is ____________________
Phosphorus pentabromide
ICl3 is _____________________
Iodine trichloride
H20 is _____________________
Dihydrogen monoxide
Strange Names for Molecules
• ANOL
• BUTANOL
• MORONIC ACID
• CRAPINON
Naming Acids
• Acids are molecular compounds that contain
hydrogen bonded to a nonmetal or to a
group of polyatomic ions.
• Acids can be either binary or ternary
compounds.
• Names of binary acids have the form
hydro-…ic acid.
• Names of ternary acids use a series of
prefixes and suffixes to specify # of oxygen
atoms in the molecule.
Naming Binary Acids
EX: Binary acid: HF is hydrofluoric acid
HCl is hydrochloric acid
Try:
H2S
HI
HBr
Naming Ternary Acids
• When naming ternary acids, identify
polyatomic ion in the formula.
• For polyions that end in “ate” change the
ending to “ic”. (Something I “ate” made me
feel “ic”.
• For polyions that end in “ite” change the
ending to “ous”.(A snake b“ite” is
poison“ous”) 
EX: nitrate  nitric
nitrite  nitrous
sulfite 
sulfate 
• When naming ternary acids from polyions
that have up to four oxygen possibilities:
per-… -ic greatest # of oxygen atoms.
-ic greater
-ous smaller
hypo-…-ous smallest # of oxygen atoms.
*Know all forms of ClO3-1 and IO3-1
Polyion Acid Formula Acid Name
ClO4-1 HClO4
perchloric acid
ClO3-1 HClO3 chloric acid
ClO2-1 HClO2 chlorous acid
ClO-1 HClO
hypochlorous acid
• Name:
HIO
HIO2
HIO3
HIO4
Naming Acids
Name the following acids:
HCl
H2SO4
H3PO4
HF
HNO3
HNO2
HC2H3O2
HClO2
HBrO3
HClO4
Writing Formulas of Acids
• Acids are molecules that are covalently
bonded yet they have properties of ionic
compounds so use rules for creating neutral
ionic compounds.
• Formulas for acids begin with Hydrogen.
The oxidation state for hydrogen is +1.
• Identify if the acid is binary or ternary. If
the acid is binary, it will have a “hydro”
prefix, all others will be ternary.
Formulas of Binary Acids
• Write H+1
• Identify the monotomic anion by its root
name in the acid.
• Determine its charge by following the
oxidation trend for the groups.
• Write the element symbol and its negative
oxidation.
• Criss Cross charges to create neutral acid
formulas.
EX: hydrosulfuric acid
H+1
S-2
H2S
Now Try:
hydrochloric acid
hydrobromic acid
hydrophosphoric acid
hydrofluoric acid
Formulas of Ternary Acids
• Write H+1
• Identify polyion by:
1. ic  ate and ous  ite suffixes
2. prefixes of per and hypo to indicate
numbers of oxygen atoms for chlorates and
iodates.
• Write formula of polyion including
oxidation.
• Criss Cross charges for neutral formula.
EX: sulfuric acid
H+1
SO4-2
H2SO4
Now try:
phosphoric acid
nitrous acid
perchloric acid
acetic acid
nitric acid
sulfurous acid
hypoiodous acid
Molecular and Empirical
Formulas
• The formulas for compounds that exist as
molecules are called molecular formulas.
EX: Hydrogen peroxide, H2O2, consists of
two H atoms and two O atoms.
• The atomic ratio of hydrogen peroxide is
one to one.
• The simplest formula that would indicate
this ratio would be HO. This simple
formula is an empirical formula.
Molecular and Empirical
Formulas
• Formulas for ionic compounds are almost
always empirical.
EX: NaBr is empirical because it takes one
sodium atom to combine with one
bromine atom to obtain a neutral charge.
*The exception is Hg+1, it is unstable so an
overall charge of +2 has to be made by two
mercurous ions.
Hg2Cl2 and Hg2(NO3)2 are correct.
Molecular and Empirical
Formulas
• C6H12O6 is molecular for Glucose
• CH2O
is empirical because we could
factor out a six from each
subscript.
• CH3COOH is molecular for Acetic Acid
• CH2O
is empirical (factor out a 2).
* Note: Glucose and Acetic Acid are very
different molecules yet they have the same
empirical formula.
•
1.
2.
3.
4.
5.
6.
7.
8.
9.
Identify each of the following as empirical or
molecular. If molecular, make empirical.
CH4
Ag2SO4
C3H9O3
N2O2
C2H4
Hg2(ClO3)2
C2H4OH
N2O5
P5O10
In Summary
• A chemical symbol for an element
represents one atom of that element when
it appears in a formula.
• A chemical formula is a statement in
chemical symbols of the composition of
one formula unit of a compound. A
subscript in a formula represents the
relative number of atoms of an element in
the compound.
In Summary
• An ion is a charged particle that is formed
when an atom gains or loses electrons.
• A polyatomic ion is a stable, charged group
of atoms.
• Oxidations numbers for monatomic ions
can be predicted from placement on the
periodic table.
• In chemical compounds, atoms combine to
form neutral charges.
In Summary
• A binary compound is composed of two
elements. Its name is the name of the
cation followed by the name of the anion
modified to end in –ide.
• Some elements have more than one
oxidation number. A compound containing
such an element is named by showing the
oxidation number as Roman numerals in
parentheses after the element.
In Summary
• A compound containing a polyatomic ion
is named in the same way as a binary
compound, except the ending of the
polyatomic ion is not changed.
• A molecular formula shows the actual
number of each kind of atom in a single
molecule of a compound.
In Summary
• An empirical formula represents the
simplest whole-number ratio between
atoms in a compound.
• A C6H12O6 production.