Periodic Table
Ions and Oxidation Numbers
Ions and Oxidation Numbers:
At the conclusion of our time
together, you should be able to:
1. Identify an ion as a cation, anion,
monatomic or polyatomic
2. Explain the charge of an ion
3. Define an oxidation number
4. List the standard oxidation number for every
element on the periodic table
5. Determine the oxidation numbers in a
compound or ion
Ions
An ion is an atom, or group of atoms, that has a
net positive or negative charge.
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wished he was…
Tin - Sn
Cation – ion with a positive charge
If a neutral atom loses one or more
electrons it becomes a cation.
Na
11 protons
11 electrons
Na+
11 protons
10 electrons
Anion – ion with a negative charge
If a neutral atom gains one or more electrons
it becomes an anion.
Cl
17 protons
17 electrons
Cl-
17 protons
18 electrons
Cation
an ion with a positive charge.
A
Anion
an ion with a Negative charge.
I
O
N
A monatomic ion contains only one atom
Na+, Cl-, Ca2+, O2-, Al3+, N3-
A polyatomic ion contains more
than one atom
OH-, CN-, NH4+, NO3-
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CONTORTIONISM.
"Will you look at that dirt on the back of
your neck!"
Do You Understand Ions?
+
27
3
How many protons and electrons are in 13 Al ?
13 protons, 10 (13 – 3) electrons
2- ?
Se
How many protons and electrons are in 78
34
34 protons, 36 (34 + 2) electrons
2.5
Oxidation Numbers
The charge the atom would have in a molecule (or an
ionic compound) if electrons were completely transferred
to the more electronegative atom.
Metal ions in Family 1, 2, 3, and 13 have one,
positive oxidation number;
Group 1 metals are
+1, Group 2 metals are
+2, Groups 3 and 13 metals are
+3.
Li+, Li = +1;
Mg2+, Mg = +2
Sc3+, Sc = +3;
Al3+, Al = +3
Oxidation Numbers
Let’s Check for Understanding:
Lithium ion =
Li+, therefore the oxidation # =
+1;
Magnesium ion =
Mg2+, therefore the ox. # =
+2
Aluminum ion =
Al3+, therefore the ox. # =
+3
Oxidation Numbers (cont.)
The oxidation number of a transition metal ion is positive,
but can vary in magnitude. Mostly
2+. Why?
Nonmetals can have a variety of oxidation numbers, both
positive and negative numbers which can vary in
magnitude. Mostly, however, Group 14 =
4+/-, Group 15 =
3-, Group 16 =
2- and Group 17 =
1-. Why?
Oxidation Numbers (cont.)
Free elements (uncombined state) have an oxidation
number of zero. Each atom in K or Be for example
has the same oxidation number:
zero.
Interesting Answers to Catholic
Elementary School Bible Questions:
MOSES LED THE JEWS
TO THE RED SEA WHERE
THEY MADE
UNLEAVENED BREAD,
WHICH IS BREAD
WITHOUT ANY
INGREDIENTS.
Assigning Oxidation Numbers
Assigning Oxidation Numbers
Alkali Metals = +1
Assigning Oxidation Numbers
Alkaline Earth Metals = +2
Assigning Oxidation Numbers
Group 13 Boron Group = +3
Assigning Oxidation Numbers
Group 15 Nonmetals = -3
Assigning Oxidation Numbers
Group 16 Nonmetals = -2
Assigning Oxidation Numbers
Halogens = -1
Assigning Oxidation Numbers
Transition and Post Transition Metals
generally have
multiple oxidation numbers
Assigning Oxidation Numbers
Except: Ag1+, Zn2+, Cd2+
Assigning Oxidation Numbers
Also, because of the glitch, these two
families will tend to be 1+, not 2+
15 Helpful Hints On The Lab Report from
Mr. T’s Vast Lab Experience!!!
Hint #2. Experiments must be reproducible.
They should fail the same way each time.
Oxidation Numbers
How to determine oxidation numbers for elements
that can have several possibilities:
The most electronegative element will generally
retain its negative oxidation number.
The least electronegative element will generally
retain its positive oxidation number.
Use this information to determine the other
oxidation numbers.
The oxidation number of fluorine is always –1. (unless
fluorine is in elemental form, F2)
The sum of the oxidation numbers of all the atoms in a
molecule or ion is equal to the charge on the molecule or
ion.
Example: CuF; F= -1; Therefore Cu =
+1
The oxidation number of hydrogen is +1
HF; F=
-1, therefore H =
+1
except when it is bonded to metals in binary compounds. In
these cases, its oxidation number is –1.
NaH; Na=
+1, therefore H =
-1
The oxidation number of oxygen is usually
–2.
In H2O2 and O22- it is
–1.
H2O; H =
+1, O=
-2
SO3; O =
-2 x 3 = -6,
S=
+6
Oxidation numbers of all
the atoms in HCO3- ?
HCO3O = -2
H = +1
3 x (-2) + 1 + ? = -1
C = +4
Find the Oxidation numbers of all the
elements in the following ?
IF7
F = -1
7 x (-1) + ? = 0
I = +7
Ions and Oxidation Numbers:
Let’s see if you can:
1. Identify an ion as a cation, anion,
monatomic or polyatomic
2. Explain the charge of an ion
3. Define an oxidation number
4. List the standard oxidation number for every
element on the periodic table
5. Determine the oxidation numbers in a
compound or ion
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underage drinking parties!
Radium - Ra
An atom has 14 protons, 18 electrons and
20 neutrons. The element (or ion) is …
1.
2.
3.
4.
5.
6.
7.
Si
Mg
Ar
Si4Si4+
Ar4Ar4+
0%
Si
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
0%
0%
13
Si4
Ar
g
M
14
0%
15
16
0%
+
Si4
17
0%
4Ar
18
0%
4+
Ar
19
20
An atom has 15 protons, 10 electrons and
17 neutrons. What element (or ion) is it?
1.
2.
3.
4.
5.
6.
Ne
P
Ne5+
P5+
Ne5P5-
0%
0%
Ne
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
0%
5+
Ne
P
13
0%
14
15
0%
5Ne
+
P5
16
0%
17
18
P5
19
20
How many total electrons does the
following ion have? F-
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
17
0%
n
0%
Te
0%
e
0%
N
in
0%
ht
O
ne
6.
0%
Ei
g
5.
n
4.
o
3.
Tw
2.
Se
ve
One
Two
Seven
Eight
Nine
Ten
1.
18
19
20
Na+ is called a(n)
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
0%
on
a
ya
t
M
Po
l
1
0%
Ip
ad
on
An
i
Cu
tio
0%
n
0%
io
0%
n
5.
to
m
ic
4.
io
n
3.
ic
2.
Cution
Anion
Polyatomic ion
Monatomic ion
Ipad
om
1.
16
17
18
19
20
NO- is called a(n)
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
ic
io
to
m
n
io
n
15
0%
on
a
M
Po
l
1
0%
Io
ni
o
0%
n
0%
ya
t
Ca
t
io
n
5.
0%
ic
4.
om
3.
n
2.
Cation
Antion
Polyatomic ion
Monatomic ion
Ionion
An
tio
1.
16
17
18
19
20
How many total electrons does the
following ion have? O2-
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
13
14
15
16
17
0%
n
0%
Te
0%
e
0%
Ni
n
0%
ht
On
e
6.
0%
Ei
g
5.
en
4.
Se
v
3.
o
2.
One
Two
Seven
Eight
Nine
Ten
Tw
1.
18
19
20
How many total electrons does the
following ion have? Mg2+
1.
2.
3.
4.
5.
6.
One
Two
Seven
Eight
Nine
Ten
0%
e
On
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
0%
Tw
13
o
14
0%
v
Se
0%
en
15
h
Eig
16
0%
t
ne
Ni
17
18
0%
n
Te
19
20
What is the general oxidation number for
Zn, z = 30?
1+
2+
3+
3210
1.
2.
3.
4.
5.
6.
7.
0%
1+
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
0%
0%
2+
13
3+
14
15
0%
0%
0%
0%
3-
2-
1-
0
16
17
18
19
20
What is the general oxidation number for
Cl, z = 17?
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
0%
12
13
0%
14
0%
15
16
0%
17
0%
0%
18
0
7.
0%
1-
6.
2-
5.
3-
4.
2+
3.
1+
2.
3+
1+
2+
3+
3210
1.
19
20
What is the general oxidation number for
Cu, z = 29?
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
0%
12
13
0%
14
0%
15
16
0%
17
0%
0%
18
0
7.
0%
1-
6.
2-
5.
3-
4.
3+
3.
2+
2.
1+
2+
3+
3210
1+
1.
19
20
What is the general oxidation number for
Ni, z = 28?
1+
2+
3+
3210
1.
2.
3.
4.
5.
6.
7.
0%
1+
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
0%
0%
2+
12
13
3+
14
15
0%
0%
0%
0%
3-
2-
1-
0
16
17
18
19
20
Which of the following is isoelectronic to
Na+?
F+
Al-3
Mg+
Ne
4.
0%
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
0%
Al
-3
F+
0%
13
14
15
0%
N
e
3.
g+
2.
M
1.
16
17
18
19
20
Which of the following is isoelectronic to
Na+?
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
0%
0%
3
Al
+
13
14
0%
+
F+
0%
N
e
Ne +
g+
4.
2.
M
3.
F+
Al+3
Mg+
1.
15
16
17
18
19
20
N3- is a(n)?
anion
cation
diatomic molecule
polyatomic ion
1.
2.
3.
4.
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
0%
io
an
13
14
n
0%
t
ca
15
16
ion
0%
0%
.
o..
cm
mi
o
t
dia
17
18
lya
po
19
mi
to
..
c.
20
NH4+ is a(n)?
anion
cution
diatomic molecule
polyatomic ion
1.
2.
3.
4.
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
0%
io
an
13
14
n
0%
n
tio
cu
15
16
0%
0%
.
o..
cm
mi
o
t
dia
17
18
lya
po
19
mi
to
..
c.
20
Na+ is a(n)?
anion
cation
diatomic molecule
polyatomic ion
1.
2.
3.
4.
1
2
3
4
5
6
7
8
9
10
21
22
23
24
25
26
27
28
29
30
11
12
0%
i
an
13
14
on
0%
t
ca
15
0%
..
o.
ion
16
0%
ic
m
ic
m
to
dia
17
l
po
18
ya
...
m
to
19
20
Oxidation numbers of all the elements in
the following ?
NaIO3
Na = +1 O = -2
3 x (-2) + 1 + ? = 0
I = +5
Oxidation numbers of all the elements in
the following ?
K2Cr2O7
O = -2
K = +1
7 x (-2) + 2 x (+1) + 2 x (?) = 0
Cr = +6
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STAMINA.
"You'll sit there until all that spinach is
gone."