Periodic Table

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 ion3. Define an oxidation number4. List the standard oxidation number for every

element on the periodic table5. Determine the oxidation numbers in a

compound or ion

An ion is an atom, or group of atoms, that has a net positive or negative charge.

Ions

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Tin - Sn

Cation – ion with a positive chargeIf a neutral atom loses one or more

electrons it becomes a cation.

Na 11 protons11 electrons

Na+ 11 protons10 electrons

Anion – ion with a negative chargeIf a neutral atom gains one or more electronsit becomes an anion.

Cl 17 protons17 electrons

Cl-17 protons18 electrons

Cation an ion with a positive charge.

Anion an ion with a Negative charge.

Cation an ion with a positive charge.

Anion an ion with a Negative charge.

A

ION

-

A monatomic ion contains only one atom

A polyatomic ion contains more than one atom

Na+, Cl-, Ca2+, O2-, Al3+, N3-

OH-, CN-, NH4+, NO3

-

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13 protons, 10 (13 – 3) electrons

34 protons, 36 (34 + 2) electrons

Do You Understand Ions?

How many protons and electrons are in Al2713 ?3+

How many protons and electrons are in Se7834

2- ?

2.5

Oxidation NumbersThe charge the atom would have in a molecule (or anionic compound) if electrons were completely transferredto 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.

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Assigning Oxidation Numbers


Alkali Metals = +1


Alkaline Earth Metals = +2


Group 13 Boron Group = +3


Group 15 Nonmetals = -3


Group 16 Nonmetals = -2


Halogens = -1


Transition and Post Transition Metals generally have

multiple oxidation numbers


Except: Ag1+, Zn2+, Cd2+


Also, because of the glitch, these two families will tend to be 1+, not 2+

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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 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 fluorine is always –1. (unless fluorine is in elemental form, F2)

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

HCO3-

O = -2 H = +1

3 x (-2) + 1 + ? = -1

C = +4

Oxidation numbers of all the atoms in HCO3

- ?

IF7

F = -1

7 x (-1) + ? = 0

I = +7

Find the Oxidation numbers of all the elements in the following ?

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 ion3. Define an oxidation number4. List the standard oxidation number for every

element on the periodic table5. Determine the oxidation numbers in a

compound or ion

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Radium - Ra

An atom has 14 protons, 18 electrons and 20 neutrons. The element (or ion) is …

0% 0% 0% 0%0%0%0%

1. Si

2. Mg

3. Ar

4. Si4-

5. Si4+

6. Ar4-

7. Ar4+

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

An atom has 15 protons, 10 electrons and 17 neutrons. What element (or ion) is it?

0% 0% 0%0%0%0%

1. Ne

2. P

3. Ne5+

4. P5+

5. Ne5-

6. P5-

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

How many total electrons does the following ion have? F-

0% 0% 0%0%0%0%

1. One

2. Two

3. Seven

4. Eight

5. Nine

6. Ten

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

Na+ is called a(n)

0% 0% 0%0%0%

1. Cution

2. Anion

3. Polyatomic ion

4. Monatomic ion

5. Ipad

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

NO- is called a(n)

0% 0% 0%0%0%

1. Cation

2. Antion

3. Polyatomic ion

4. Monatomic ion

5. Ionion

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

How many total electrons does the following ion have? O2-

0% 0% 0%0%0%0%

1. One

2. Two

3. Seven

4. Eight

5. Nine

6. Ten

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

How many total electrons does the following ion have? Mg2+

0% 0% 0%0%0%0%

1. One

2. Two

3. Seven

4. Eight

5. Nine

6. Ten

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

What is the general oxidation number for Zn, z = 30?

0% 0% 0% 0%0%0%0%

1. 1+

2. 2+

3. 3+

4. 3-

5. 2-

6. 1-

7. 01 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

What is the general oxidation number for Cl, z = 17?

0% 0% 0% 0%0%0%0%

1. 1+

2. 2+

3. 3+

4. 3-

5. 2-

6. 1-

7. 01 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

What is the general oxidation number for Cu, z = 29?

0% 0% 0% 0%0%0%0%

1. 1+

2. 2+

3. 3+

4. 3-

5. 2-

6. 1-

7. 01 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

What is the general oxidation number for Ni, z = 28?

0% 0% 0% 0%0%0%0%

1. 1+

2. 2+

3. 3+

4. 3-

5. 2-

6. 1-

7. 01 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

Which of the following is isoelectronic to

Na+?

0% 0%0%0%

1. F+

2. Al-3

3. Mg+

4. Ne

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

Which of the following is isoelectronic to Na+?

0% 0%0%0%

1. F+

2. Al+3

3. Mg+

4. Ne +

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

N3- is a(n)?

0% 0%0%0%

1. anion

2. cation

3. diatomic molecule

4. polyatomic ion

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

NH4+ is a(n)?

0% 0%0%0%

1. anion

2. cution


4. polyatomic ion

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

Na+ is a(n)?

0% 0%0%0%

1. anion

2. cation


4. polyatomic ion

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

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

Oxidation numbers of all the elements in the following ?

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STAMINA.

"You'll sit there until all that spinach is gone."

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Periodic Table