121_nomenclature_rul..

1
The following notes are modified from Chapter 2 (pp 11-15) and Chapter 3 (pp11-13)
Compound: a substance composed of two or more elements in fixed proportions
• Compounds can be divided into two categories:
a. covalent compounds and
b. ionic compounds.
Covalent Compounds
• Covalent bonds arise when two atoms share a pair of
electrons between them in localized atomic orbitals. The
mutual attractions of their (positively charged) nuclei for the
(negatively charged) electrons hold the atoms together.
• Molecules are always held together by covalent bonds.
• In most all cases, covalent bonds occur between nonmetal atoms. Examples:
H
C
H
H
N
H
H
H
H
H
F
H
water
ammonia
methane
O
H
hydrogen fluoride
Ionic Compounds
• Ionic bonds occur between cations and
anions due to the "electrostatic attraction"
of positive charge for negative charge.
• In an ionic solid, electrons are not shared in
localized orbitals between the atoms. Instead, a
given cation is attracted to any and all anions in
all 3 dimensions of the solid (with the strength
of the attraction falling off rapidly with
increasing distance) and vice versa. They are
never referred to as molecules.
• Ionic bonds occur between metal and nonmetal atoms. Many elements form only one type of
charge for its ion (memorize these). Other metals have multiple charge possibilities; figure
out charge from bonded anions. Ionic compounds are always formed such that there is no net
charge on the compound. By convention always use the smallest whole number ratio of
elements.
Examples:
Li2O
NaI
FeCl3
Fe2S3
2
1A
8A
7A
Main Group Elements
+
Transition Metal Elements
Ag = silver
Co = cobalt
Cd
= cadium
Ti = titanium
Ni = nickel
Pt
=
platinum
V = vanadium
Cu = copper
Au
=
gold
Cr = chromium
Zn = zinc
Hg
=
mercury
Mn = manganese
Rh = rhodium
La = lanthanum
Pd = palladium
Fe = iron
8B
2B
3B 4B 5B
6B 7B
1B
Sc = scandium
_
H
H
hydrogen
+
Li
2A
3A
+
+
+2
+
Cs
cesium
-2
Se
gallium
Sr
_
+3
Br
Sc
Te
barium
+2
+2
+2
+2
+2
+3
+2
Cr
Ni
Cu
Mn Fe Co
+3
+3
+3
+4
+4
+ Zn
Cr
Co
Cu
Mn
Ni
Fe
+3
I
Rh
Pb+2
Pb+4
Ba
+3
V
teluride iodide
tin
+2
+3
Ti
selenide bromide
_
-2
Sn+2
Sn+4
+2
Cl
S
+3
rubidium strontium
+
sulfide chloride
Ga
potassium calcium
Rb
aluminium
Al
Ca
F
O
+3
+2
Mg
hydride
_
-2
oxide fluoride
_
-2
carbide nitride
sodium magnesium
K
N
C2
lithium beryllium
6A
-3
-2
+2
Be
Na
5A
4A
+2
+
Pd
+4 Ag
Pd
+2
Cd
+2 Au + Hg2+2
Pt
+3
+2
Pt +4 Au Hg
+3
La
lead
• A "polyatomic ion" is a covalently bonded group of nonmetal atoms (molecule) that is charged.
Although covalent bonds hold the atoms of the polyatomic ion together as a unit (molecule), an
ionic bond exists between the polyatomic ion and its "counter ion". You are responsible for
those listed on page 7 of this handout. Some examples:
O
O
O
N
N
O
O
C
O
O
H
O
O
S
O
nitrite anion = NO2
N
H
H
O
nitrate anion = NO3
H
O
carbonate anion = CO3-2
sulfate anion = SO4-2 ammonium cation = NH4+
How many formulas are correct below?
NaCl2
Al3S2
CaF2
Cd(NO2)3
FeCO3
KSO4
MgN
CuBr3
Ga2(SO4)3
LiI
a. 2
b. 4
c. 6
d. 8
e. no correct answer
Metallic bonds will be studied later in the course. For now, metals tend to have fewer valence
electrons. Their outermost valence electrons are held more loosely, and they have more empty
orbitals in their valence shell. The valence electrons are shared by all of the metal atoms, which
allows metals to conduct electricity and heat. They are often easily deformed and lustrous in
appearance. Some examples:
Fe
Cu
Ag
Hg
Pd
Pt
Zn
Na
Mg
3
Place check marks for all of the categories that apply:
Au
CH3OH
KI
N2
NaNO3
Element?
Compound?
Molecule?
Covalent?
Ionic?
Metallic?
Nomenclature of Binary Compounds
Binary Compound: compound composed of only 2 different elements (e.g., P2O5, KBr, HCl (aq))
All Binary Compounds
Covalent Compounds
H2O, CO, CO2, HCl, N2O4, NF3, SO3, CH4
Aqueous Acids
dissolved in H2O
Ionic Compounds
H2S(aq), HCl(aq), HBr(aq), HI(aq)
Metals with Only One
Oxidation State
NaCl, Na2O, BeI2, BeO, AlBr3, Al2O3
Metals with Multiple
Oxidation States
FeCl2, FeCl3, Cu2O, CuO, CrO, Cr2O3
All Ionic Compounds: The following two rules apply to ALL ionic compounds:
a. metal only has one oxidation state
first part of name
second part of name
NaO = sodium oxide
metal cation
space
anion root + -ide
(use elemental name)
suffix
b. metal has more than one oxidation state
first part of name
space
metal cation (roman numerals
indicating charge)
(use elemental name)
second part of name
anion root + -ide
suffix
FeO = iron(II) oxide
Fe2O3 = iron(III) oxide
4
Keep the following in mind:
• You must memorize that the following metals have only one oxidation state: Group IA
(always 1+), Group IIA (always 2+), Al3+, Ag+, Zn2+, and Cd2+. Most other metal cations
have multiple oxidation states available.
•
For cations that have multiple oxidation states available, the oxidation state must be
determined based on knowledge of the anion charge and the principle of
electroneutrality. For example, oxide has a -2 charge, O-2. The charge on the metal
cation is indicated with roman numerals in parentheses.
•
Prefixes indicating number (e.g., mono, di, tri, tetra, etc.) are never used when naming
ionic compounds.
_
simple anions =
polyatomic anions =
cations
transition metals
single
and
oxidation
states multiple oxidation states
+
1*H
2
15
Li +
3 Na
4
K
+
+
5 Rb
+
+3
16
Ti
17
V
18,19
+2
Cr
+2
24,25
Co
9 Ca +2
26,27
Ni
10 Sr+2
28,29
Cu + Cu+2
Fe
+2
Co
+2
Zn
+3
31
Rh
32,33
Pd
34
Ag
35
Cd
36,37
Pt
_
F
h
_
Cl
i
_
Br
j
_
I
k
C2H3O2OHCO32C2O4-2
ClOClO4ClO2- ClO3CNhydroxide carbonate cyanide (or CH3COO ) oxalate hypochlorite chlorite chlorate perchlorate
p
l
m
q
t
acetate
n
s
r
o
NO2BrO3MnO4CrO42IO4PO43Cr2O72SO42- SO32- NO3
sulfate sulfite nitrate nitrite phosphate permanganate chromate dichromate bromate periodate
u
v
w
z
aa
cc
dd
y
bb
x
What is the roman numeral that would go with each of the following metals?
b. MnO2
c. RhO3
d. Fe2O3
e. V2O5
c. (IV)
d. (V)
f. HgO
g. UO2
e. (VI)
+3
Pick any combination of numbers and letters and provide an acceptable name.
That should total (46)x(30) = 1380 possibilities!
+4
Ni
+3
+2
Pd
+4
+
38,39
polyatomic
40,41
cation
14 NH4+
ammonium
-2
Te
g
+2
30
+3
-2
Se
f
+3
+2
+2
13 Ga
-2
+3
Cr
Fe
12 Al
S
e
+2
22,23
11Ba
b
-2
O
d
Possible answers:
a. (II)
b. (III)
+3
+2
8 Mg
a
-3
N
c
+3
Mn Mn+4
7 Be
C2
a. OsO4
Sc
20,21
6 Cs +
-2
H
+2
+2
Pt +4
+3
Au + Au
+2
Hg2+2 Hg
42,43
Sn+2 Sn+4
44,45
Pb+2 Pb+4
46
+3
La
* always comes attached to a pair of electrons (H3O+, NH4+, etc.)
5
Covalent Compounds
The following three rules apply to ALL covalent compounds:
Binary covalent compounds will consist of two nonmetals. The more "cation-like" element name
comes first, followed by the more "anion-like" stem name with an “-ide suffix”. Leaving a space
in-between the two names. Indicate the number of both nonmetals by using appropriate
numerical prefixes in front of both the more cation-like and the more anion-like element.
Keep the following in mind:
• When the prefix ends in an "a" or an "o" and the anion name begins with a vowel, the "a"
or the "o" on the prefix is dropped to avoid having two vowels together (e.g., monoxide
instead of monooxide and tetroxide instead of tetraoxide).
• The "mono" prefix is never used for the element named first. For example, CO is carbon
monoxide, not monocarbon monoxide.
• Two covalent compounds have such common names that the above systematic rules are
never used: H2O (_________________) and NH3 (__________________).
Numerical Prefixes for
Naming Compounds
Prefix
monoditritetrapentahexaheptaoctanonadeca-
More
anion-like
More
cation-like
Meaning
1
2
3
4
5
6
7
8
9
10
If the anion stem starts
with a vowel, drop the "a"
or "o" of the prefix name.
Keep the "i" vowel.
How many formulas are correctly written below (combination of ionic and covalent compounds)?
NaCl
Al2O3
F2O
HF
Fe2O3
NH3
SK2
HLi
CuBr2
NGa
LiI
CH4
a. 2
b. 4
c. 6
d. 8
e. no correct answer
How many formulas represent covalent compounds? (Same answer choices.)
6
Aqueous Acids
This is a special class of compounds that require different nomenclature rules. They can be
identified by the following:
• Hydrogen will be the first element in the chemical formula, and the second element will be
from Group VIA (S, Se, Te, - O is special = water) or VIIA (F, Cl, Br, I).
• The compound will be dissolved in water, which is referred to as being "aqueous" and
indicated with a subscript of "(aq)" (e.g., HCl (aq) or H2S (aq)).
For these aqueous acids, use the following two rules:
• Always start the name with a "hydro" prefix.
• Always end the name with "ic" added to the "root" of the non-hydrogen element's name
followed by the separate word "acid".
Keep the following in mind:
• Only use the above rules when these compounds are in aqueous solution (i.e., have the
"(aq)" subscript). If they are not dissolved in water, they must be named using the normal
rules for molecular compounds.
• Prefixes indicating number (e.g., mono, di, tri, tetra, etc.) are never used when naming
aqueous acids.
Provide acceptable names for the following compounds.
H2S(aq), H2Se(aq), H2Te(aq), HF(aq), HCl(aq), HBr(aq),
b. H2S, H2Se, H2Te, HF, HCl, HBr, HI
a.
HI(aq)
7
Nomenclature of Ternary Compounds
Ternary Compound: compound composed of 3 or more different elements (e.g., NaNO3, H3PO4)
The nomenclature of ternary compounds can be divided into two categories, ionic compounds
and acids. We will not consider ternary covalent compounds in this course.
Ionic Compounds
• Ternary ionic compounds will always include at least one
polyatomic ion, so it is critical that you memorize their
names, formulas, and charges.
• Just like the nomenclature of the binary compounds, it is
essential that you know which elements form cations of
only one oxidation state and which ones form cations of
multiple oxidation states. As before, only cations that
form multiple oxidation states require indication of the
oxidation state using Roman numerals.
• The ammonium ion, NH4+, is the only cationic polyatomic
ion we will consider, although there are many others.
• Name the cation first as the element name (or
"ammonium"). Name the anion second using the name of
the polyatomic ion.
See chart on page 4 for many nomenclature possibilities.
Polyatomic Cations
Formula
Name
+
NH4
ammonium
Polyatomic Anions
Formula
Name
hydroxide
OH
2carbonate
CO3
cyanide
CN
C2H3O2
acetate
(or CH3COO )
C2O42oxalate
hypochlorite
ClO
chlorite
ClO2
chlorate
ClO3
perchlorate
ClO4
bromate
BrO3
periodate
IO4
2sulfate
SO4
2sulfite
SO3
nitrate
NO3
nitrite
NO2
3phosphate
PO4
permanganate
MnO4
chromate
CrO42
2dichromate
Cr2O7
8
Oxo Acids
• This is a special class of compounds that require different nomenclature rules.
• Hydrogen will be the first element in the chemical formula, followed by a (non-hydrogen,
non-oxygen) nonmetal and then oxygen (e.g., HNO3, H2SO4, or HClO3).
• Because they all contain oxygen, they are sometimes referred to as "oxoacids".
• Always name as the acid whether or not they are aqueous (e.g., HNO3 or HNO3 (aq)).
Most of the nonmetal elements form more than one oxoacid that differ only by the number of oxygen atoms in the formulas. One
ternary acid for each non-metal is designated as the reference acid, and the others are named in
reference to it by using prefixes and suffixes determined by the number of oxygen atoms present.
Group IIIA
H3BO3
boric acid
Reference Acids
Group VA
HNO3
nitric acid
H3PO4
phosphoric acid
H3AsO4
arsenic acid
Group IVA
H2CO3
carbonic acid
Group VIA
Group VIIA
H2SO4
sulfuric acid
H2SeO4
selenic acid
HClO3
chloric acid
HBrO3
bromic acid
HIO3
iodic acid
HClO4
perchloric acid
Reference
Acids
HNO3
nitric acid
H2SO4
sulfuric acid
H3PO4
phosphoric acid
HClO3
chloric acid
HNO2
nitrous acid
H2SO3
sulfurous acid
H3PO3
phosphorus acid
HClO2
chlorus acid
H3PO2
hypophosphorus acid
Prefix
Prefixes and Suffixes
Formula
Suffix
Name
HClO
hypochlorus acid
Anion
Anion Name
-ic
HClO4
perchloric acid
ClO4-
perchlorate
Reference acid
-ic
HClO3
chloric acid
ClO3-
chlorate
1 less oxygen
-ous
HClO2
chlorous acid
ClO2-
chlorite
-ous
HClO
hypochlorous acid
ClO-
hypochlorite
1 more oxygen
2 less oxygens
per-
hypo-
9
Provide acceptable names for the following salts.
NaClO4
NaNO3
Na2SO4
Na3PO4
NaClO3
NaNO2
Na2SO3
Na3PO3
NaClO2
Na3PO2
NaClO
Name the following compounds: (always lower case)
KH ____________________________
Cr2S3 __________________________
CuCl2 __________________________
BaBr2 __________________________
NF3 ____________________________
CCl4 ___________________________
Cl2O7 __________________________
P4O6 ___________________________
HBr (aq) _________________________
H2S (aq) _________________________
HBr ____________________________
H2S ____________________________
NaNO3 _________________________
Fe3(PO4)2 _______________________
NH4ClO4 _______________________
(NH4)2SO4 ______________________
HBrO4 _________________________
H2SO3 _________________________
HNO2 __________________________
HBrO (aq)_______________________
Write the chemical formula indicated by the following names:
sodium oxide _____________________
iron(II) nitride ____________________
sulfur tetrafluoride ________________
dinitrogen trioxide _____________
hydriodic acid ____________________
hydroselenic acid _________________
hydrogen iodide___________________
hydrogen selenide _________________
potassium carbonate _______________
chromium(III) hydroxide ____________

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