Chapter 7 (7.1-7.10, not 7.6): Chemical Bonds
  valence electrons are in the outer most regions of the atom
  ions form by losing or gaining electrons
  When an electron is lost it is one of the valence electrons
that is lost
  special stability is associated with a filled shell electron
configuration (noble gas electron configuration)
  some extra stability with a half filled shell
1
The Octet Rule
see Chapter 7.3
  In forming compounds, atoms of elements lose, gain, or
share electrons in such a way as to produce a noble gas
electron configuration for each of the atoms involved.
  Octet: a noble gas electron configuration has 8 valence
electrons (except for He) in an ns2np6 electron
configuration
»  Ne: 1s2 2s22p6
2
Types of Compounds
Ionic Compounds
Molecular Compounds
From the combination of
anions and cations
NaCl
MgBr2
From the combination of
neutral atoms
H2O
CCl4
Dissolved in water, ions
dissociate and move freely
in solution
Solutions of ionic
compounds tend to conduct
electricity
When dissolved in water
the molecules remain in
their units
Solutions of molecular
compounds tend not to
conduct electricity
3
Ionic Compounds
  Ionic compounds are made up of cations and anions, in
such a way that the charge balances to give a neutral
compound
  Formation of Ions in relation to position in the periodic
table:
general observation:
metallic elements tend to form cations
non metallic elements tend to form anions
Why?
4
Ion Formation and the Periodic Table
  Group IA, the Alkali Metals
Na
→
1s22s22p63s1
Na+ + e1s22s22p6
electron configuration of
neon
All the Alkali Metal elements will tend to lose 1 electron to
form a +1 cation that has the same electron configuration
as the preceding Noble gas element
The ion has 8 valence electrons.
5
 Group IIA, the Alkaline Earth Metals
Ca
Ca2+ + 2e-
→
1s22s22p63s23p64s2
1s22s22p63s23p6
electron configuration of
argon
All Alkaline Earth Metal elements tend to lose 2 electrons
to form +2 cations with the same electron configuration
as the preceding Noble gas element.
The ion has 8 valence electrons
6
  Group VIIA, the Halogens
F + e1s22s22p5
→
F-
1s22s22p6
electron configuration of neon
All halogen elements tend to gain 1 electron to form a
–1 anion, with the same electron configuration as the
next Noble gas element
The ion has 8 valence electrons
7
The Case of Hydrogen
H
1s1
→
H + e1s1
H+ + e-
→
H1s2
electron configuration of Helium
filled shell electron configuration
Hydrogen is happy with two electrons to fill 1s subshell
Duet rule for hydrogen
8
Formation of Ions
Atoms will form ions by taking the shortest route to a noble
gas electron configuration
ie to get 8 valence electrons, a filled shell,
or 2 valence electrons in the case of hydrogen
9
Valence Electrons and Ion Formation
  # of valence electrons in an atom can generally be
determined by counting to the element, from left to right
across the row, through the s and p blocks
  tells us how many electrons are in the highest shell (n)
  atoms will form ions to obtain a noble gas electron
configuration - the shortest route to 8 valence electrons
  Will an atom with 6 valence electrons lose 6, to form a 6+
cation or gain 2 to form a 2- anion?
shortest route is to gain 2 electrons
and become a 2- anion
  electrons are lost from the valence shell
10
Period number, highest occupied electron level
Representative
07_116
Elements
1A Group
ns1
numbers
H
1s1
2
Li
2s1
3
11
12
Na
3s1
Mg
3s2
3
19
2A
ns2
p block
20
4
K
4s1
5
37
38
Rb
5s1
Sr
5s2
6
Cs
6s1
55
s block
4
Be
2s2
Ca
4s2
56
Ba
6s2
87
88
Fr
7s1
Ra
7s2
ns2np6
2
5
6
7
8
9
10
13
14
15
16
17
18
B
C
N
O
F
Ne
2
1
2
2
2
3
2
4
2
5
2s 2p 2s 2p 2s 2p 2s 2p 2s 2p 2s22p6
d block
Al
Si
P
S
Cl
Ar
3s23p1 3s23p2 3s23p3 3s23p4 3s23p5 3s23p6
21
22
23
24
25
26
27
39
40
41
42
43
44
45
28
29
30
31
32
33
34
35
36
46
47
48
49
50
51
52
53
54
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
4s23d1 4s23d2 4s23d3 4s13d5 4s23d5 4s23d6 4s23d7 4s23d8 4s13d10 4s23d10 4s24p1 4s24p2 4s24p3 4s24p4 4s24p5 4s24p6
Y
Zr
Nb
Mo
Tc
Ru
Rh
5s24d1 5s24d2 5s14d4 5s14d5 5s14d6 5s14d7 5s14d8
57
72
La*
6s25d1
4f146s25d2
Hf
89
104
73
74
75
76
105
106
107
108
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
4d10 5s14d10 5s24d10 5s25p1 5s25p2 5s25p3 5s25p4 5s25p5 5s25p6
77
78
109
110
79
80
81
82
Ce
59
Pr
83
84
85
86
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
6s25d3 6s25d4 6s25d5 6s25d6 6s25d7 6s15d9 6s15d10 6s25d10 6s26p1 6s26p2 6s26p3 6s26p4 6s26p5 6s26p6
Ac** Unq Unp Unh Uns Uno
7s26d1 7s26d2 7s26d3 7s26d4 7s26d5
58
Actinides**
He
1s2
3A
4A
5A
6A
7A
ns2np1 ns2np2 ns2np3 ns2np4 ns2np5
Une Uun
7s26d7
111
Uuu
f block
f - Transition Elements
Lanthanides*
Noble
gases
8A
Representative Elements
1
1
7
d - Transition Elements
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
6s24f15d1 6s24f35d0 6s24f45d0 6s24f55d0 6s24f55d0 6s24f75d0 6s24f75d1 6s24f95d0 6s24f105d0 6s24f115d0 6s24f125d0 6s24f135d0 6s24f145d0 6s24f145d1
90
91
92
93
94
95
96
97
98
99
100
101
102
103
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr
7s2f06d2
7s25f26d1 7s25f36d1 7s25f46d1 7s25f66d0 7s25f76d0 7s25f76d1 7s25f96d0 7s25f106d0 7s25f116d0 7s25f126d0 7s25f136d0 7s25f146d0 7s25f146d1
11
Prediction:
  Metals may react with nonmetals to form ionic
compounds.
Na +
Cl2
→
NaCl
  Structure:
12
Types of Compounds: Molecular Compounds
 
Atoms in a molecular compound are held together by
sharing of electrons, forming a covalent bond.
 
Tend to involve only non-metallic elements:
H2O, CO2, N2O,
CCl4
 
When dissolved in water the molecules remain in their
units
 
Solutions of molecular compounds generally do not
conduct electricity
13
Types of Compounds: Ionic Compounds
 
Anions and cations are held together by strong
electrostatic interactions (opposite charges attract)
 
From the combination of a cation of a metallic element
with an anion of a non-metallic element
CaCl2
 
Fe2O3
OR: combinations involving polyatomic ions
Na2SO4
(NH4)2CO3
MnO4-
 
Dissolved in water, ions dissociate and move freely in
solution
 
Solutions of ionic compounds generally conduct electricity
14
Writing Chemical Formula
Formula for Ionic Compounds
1. Cation is always written first.
2. Total (+)ve charge = total (-)ve charge.
3. Contains the simplest set of subscripts giving the ratio
of cations to anions.
K+ +
Ca2+ +
Br2 x Cl-
KBr
CaCl2
15
Polyatomic Anions
see Textbook Table 8.4
  A charged species made up of a group of atoms.
  Atoms within a polyatomic ion are held together by strong
covalent bonds.
  Generally maintain their identity as a unit.
NO3-
NH4+
SO42-
2 x Na+ + SO42-
Na2SO4
Ca2+ + 2 x NO3-
Ca(NO3)2
16
Writing Formula for Molecular Compounds
Formula reflects the actual number and types of atoms in the
molecular unit.
Generally the atoms written first are those that are to the left,
in the periodic table.
CO2
PCl5
H2O
17
Practice
  Consider the following lists of compounds:
LiF, NH4NO3, H2S, NiBr2 , I2, H2, Al2S3
  Classify each of these compounds as ionic or molecular.
18
Nomenclature of Ionic Compounds
Chapter 8
IUPAC: International Union of Pure and Applied Chemistry
Binary Ionic Compounds
contain two monatomic ions
Type I
  cation is a fixed charge metal
  name cation first then anion
  cation: name same as element
  anion: root name plus ide ending
 
 
 
NaCl sodium chloride
CaS calcium sulfide
MgF2 magnesium fluoride
19
Nomenclature: Binary Ionic Compounds
Type II
  cation is a variable charge metal (see Table 8.1)
  name must specify which cation is present
  Name of cation, charge in brackets, name of anion
FeCl2
iron(II)chloride
FeCl3
iron(III)chloride
20
Naming Polyatomic Ions
Common Names:
CN- cyanide
NH4+ ammonium
SCN- thiocyanate
Oxyanions:
-occur in series with one element (X) and different numbers of
oxygen atoms
eg:
XO2- , XO3Two in a series:
smaller # of oxygens
-ite
larger # of oxygens
-ate
SO32- sulfite
SO42- sulfate
NO2- nitrite
NO3- nitrate
21
Naming Polyatomic Ions
More than two in a series:
fewest oxygens
small# oxygens
larger # oxygens
largest # oxygens
hypo___-ite
-ite
-ate
per___-ate
ClO- hypochorite
ClO2chlorite
ClO3chlorate
ClO4perchlorate
  a similar series exists for each or F, Cl, Br, I
22
Naming Compounds that contain Polyatomic Ions
1. 
Compounds containing a fixed charge metal plus a polyatomic ion:
-give the name of the cation followed by the name of the
polyatomic ion
KNO3
2. 
potassium nitrate
Compounds containing a variable charge metal plus polyatomic
ion:
-give the name of the cation, the charge in brackets, followed
by the name of the polyatomic ions
Fe(NO3)3
iron(III)nitrate
23
Naming Binary Molecular Compounds
  Usually contain two different non-metallic elements
first element:
second element:
use full element name
root + -ide
Use prefixes to indicate number of each element:
*mono
di
tri
tetra
*mono
1
2
3
4
penta
hexa
hepta
octa
5
6
7
8
not used for the first element in a formula
24
Examples
NO
CO2
N2O5
PCl5
25
Binary Molecular Compounds with Common Names
See Table 8.6 in the textbook
  H2O
  NH3
  H2O2
  CH4
26
Acids
  Generally:
  Acids are molecular compounds that contain hydrogen
and dissolve in water to yield H+, hydrogen ions. These
solutions exhibit characteristic properties.
 
Generally** the formula of acids have hydrogen as the
first element in the formula
 
e.g. HCl, HNO3 are acids,
acids
** some exceptions:
NH3, CH3OH are not
CH3COOH is an acid (acetic acid)
27
Naming Acids
  Non Oxyacids
-contain hydrogen and one or more non metals, but not
oxygen
Two Names:
a) compound name when not dissolved in water
(anhydrous)
b) compound name when dissolved in water to produce
an acid solution
28
Gas(g)
Dissolved in water(aq)
HF(g)
hydrogen fluoride
HF(aq)
hydrofluoric acid
HCl(g)
hydrogen chloride
HCl(aq)
hydrochloric acid
HBr(g)
hydrogen bromide
HBr(aq)
hydrobromic acid
HI(g)
hydrogen iodide
HI(aq)
hydroiodic acid
H2S(g)
hydrogen sulfide
H2S(aq)
hydrosulfuric acid
29
Naming Oxyacids
In solution, oxyacids give some H+ ions and oxyanions
but
Oxyacids are not ionic compounds.
H2SO4
HNO3
H2SO3
HNO2
Ternary acids, three different elements in the chemical
formula
30
Naming Oxyacids
To name:
take name of polyatomic ion
change ending
-ite
to
-ous acid
HNO2
(NO2- nitrite)
-ate
HNO3
to
(NO3- nitrate)
nitrous acid
-ic acid
nitric acid
31
Name the polyatomic ion:
ClOClO2ClO3ClO4  Name the acid:
»  HClO
»  HClO2
»  HClO3
»  HClO4
32
Summary
Classifying a Compound for Naming
Compound
Molecular
Nonacid
Ionic
Acid
Oxyacid
Binary Ionic
Non-oxyacid
Fixed charge metal
Ternary Ionic
Variable charge metal
33
Household Chemicals
Common
Name
water
Chemical Name
Formula
salt
sodium chloride
NaCl
baking soda
sodium
bicarbonate
NaHCO3
vinegar
acetic acid
CH3COOH
Rolaids
dihydroxy
aluminum sodium
carbonate
Al(OH)2NaCO3
Tums
calcium carbonate
CaCO3
Bleach
sodium
hypochlorite
NaClO
H2O
34