Ionization Energies

Originated 11/20/11Last revision 05/19/12

Mike JonesPisgah High School

Canton NC

Ionization energy

The energy needed to remove an electron completely from at atom.

Depends upon ….

The attraction between the positively charged nucleus and the negatively charged electron.

The repulsion between the negatively charged electrons.

Ionization energy

The energy needed to remove an electron completely from at atom.

F =kq1q2

r2

Coulomb’s Law

Force of attraction

a constant

the effective nuclear charge

the charge of the electron

the distance between the nucleus and the electron

As applied to the atom

Some of the attraction of the outermost electron to the nucleus is reduced because of repulsion between the outermost electron and the remaining electrons. The apparent charge on the nucleus is called the effective nuclear charge, Zeff.

The ionization energy is high when there is a strong force of attraction between the nucleus and the outermost electrons.

With a low ionization energy, there is less attraction between the nucleus and the electron.

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500Helium has a very large ion ionization energy, which indicates a very strong attraction between the nucleus and the electron. That electron is at a lower energy, and a large amount of energy is needed to remove the electron.

The ionization energy of lithium is very low, which indicates a weak attraction. That electron is already at a higher energy and little additional energy is needed to remove the electron.

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500Ionization energy is a periodic property. The peaks are the inert gases. The valleys are the alkali metals. See how the pattern repeats for each period

H

He

Li

Be B

C

N O

F

Ne

Na

Mg Al

Si

P S

Cl

Ar

K

Ca

0

500

1,000

1,500

2,000

2,500

H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca

The ionization energy generally increases along a period as the atomic number increases and the charge on the nucleus increases. This produces more attraction between the nucleus and the electron, resulting in more energy being needed to remove the electron.

Ar

K

Ca Sc Ti V Cr

Mn Fe Co Ni Cu

Zn

Ga

Ge

As Se

Br

Kr

Rb

Sr

0

200

400

600

800

1,000

1,200

1,400

1,600

Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr

The ionization energy increases very little for the first row of the transition metals despite an increase in the number of protons.

The effective nuclear charge of the transition metals increases only marginally, and the sizes of the atoms remain close to the same.

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

2

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

2

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

2

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

2

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

2

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

2

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

2

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

2

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82 8

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82 8

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82 8 18

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82 8 18

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82 8 18 18

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82 8 18 18

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

+

82 8 18 18

28

8

18

18

32

H

He

Li

Be B

C

N O

F

Ne

Na

Mg Al

Si

P S

Cl

Ar

K

Ca

0

500

1,000

1,500

2,000

2,500

H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca

Q. Eight electrons are filling the second energy level.Why does the ionization energy increase along a period?

A. The number of protons is increasing and Zeff increases.

H

He

Li

Be B

C

N O

F

Ne

Na

Mg Al

Si

P S

Cl

Ar

K

Ca

0

500

1,000

1,500

2,000

2,500

H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca

Why are there “blips” in the ionization energies?

H

He

Li

Be B

C

N O

F

Ne

Na

Mg Al

Si

P S

Cl

Ar

K

Ca

0

500

1,000

1,500

2,000

2,500

H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca

One hypothesis is that there are two energy sublevels, very close together, making up the second energy level..

Going from Be to B, goes from one sublevel to the other and less additional energy is needed to remove an electron from the sublevel with the greater energy.

H

He

Li

Be B

C

N O

F

Ne

Na

Mg Al

Si

P S

Cl

Ar

K

Ca

0

500

1,000

1,500

2,000

2,500

H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca

Electrons in the lower sublevel

Electrons in the higher sublevel

One hypothesis is that there are two energy sublevels, very close together, making up the second energy level..

Going from Be to B, goes from one sublevel to the other and less additional energy is needed to remove an electron from the sublevel with the greater energy.

H

He

Li

Be B

C

N O

F

Ne

Na

Mg Al

Si

P S

Cl

Ar

K

Ca

0

500

1,000

1,500

2,000

2,500

H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca

The same is true for the third energy level.

Electrons in the lower sublevel

Electrons in the higher sublevel

There are many limitations of the Bohr model, including the fact that the calculations work only for hydrogen.

But there is one overriding reason why the Bohr model is so important to our study of the atom and the arrangement of electrons.

The Bohr model tells us that electrons are located only in certain, discrete energy levels and that they can only change from one energy level to another by gaining or losing energy.

1

2

3

4

The Bohr model of hydrogen. There are only a few discrete energy levels.

The “excited electron” is located in one of these energy levels

The ground-state electron is located in the lowest energy level.

n 2n2

1 2

2 8

3 18

4 32

5 50

The number of electrons in the nth energy level is given by 2n2.

The Bohr model showed only 8 electrons in the third energy level. Where are the other ten electrons?

The Quantum mechanical model deals with mulit-electrons atoms with many more energy levels.

1

2

3

4

Except for the first energy level, each energy level in the Bohr model is “subdivided” into two or more “sublevels.”

n 2n2

1 2

2 8

3 18

4 32

5 50

n is the “principal quantum number, one of 4 numbers that uniquiely describe each electron in an atom

The Quantum mechanical model has more energy levels available to electrons

n 2n2

1 2

2 8

3 18

4 32

5 50

In multi-electron atoms the original Bohr energy levels are split into sublevels.

1

2

3

4

n 2n2

1 2

2 8

3 18

4 32

5 50

In multi-electron atoms the original Bohr energy levels are split into sublevels.

1

2

3

4

n 2n2

1 2

2 8

3 18

4 32

5 50

In multi-electron atoms the original Bohr energy levels are split into sublevels.

1

2

3

4

Overlap between energy sublevels.

n 2n2

1 2

2 8

3 18

4 32

5 50

In multi-electron atoms the original Bohr energy levels are split into sublevels.

1

2

3

4

1s

2s

2p

3s

4s

3p

4p

3d

4d4f The letters s,

p, d and f are used to label the sublevels.

s = sharp

p = principal

d = diffused

f = fundamental

n 2n2

1 2

2 8

3 18

4 32

5 50

In multi-electron atoms the original Bohr energy levels are split into sublevels.

1

2

3

4

1s

2s

2p

3s

4s

3p

4p

3d

4d4f

sublevel number of electrons

s 2

p 6

d 10

f 142

8

18

32

The letters s, p, d and f are used to label the sublevels.

Periodic table - Sublevels

s pd

f2 610

14How many electrons go in each region?

Since we can’t see atoms or the electrons we have know idea what they actually look like. Yet we need a way to represent the organization of electrons in an atom.

Much like technicians use a schematic diagram to represent the components in an electronic circuit, chemists use the electron energy diagram to represent electrons in an atom.

Much like technicians use a schematic diagram to represent the components in an electronic circuit, chemists use the electron energy diagram to represent electrons in an atom.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

6s 4f5d

6p7s

5f6d

7p

E n

e r

g

y

Electron Energy Diagram

n 2n2

1 2

2 8

3 18

4 32

5 50

s 2

p 6

d 10

f 14

The electron energy diagram is a “schematic diagram” of an atom, representing the arrangement of electrons. It consists of numbers, letters and lines denoting the orbitals in the various energy sublevels.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

6s 4f5d

6p7s

5f6d

7p

E n

e r

g

y

Electron Energy Diagram

n 2n2

1 2

2 8

3 18

4 32

5 50

s 2

p 6

d 10

f 14Each of the lines represents an “orbital” where up to two electrons can be located.

The number is the principal quantum number, n.

An orbital is a “region in space” within an atom where up to two electrons can be located.

An s-orbital is spherical. Two electrons.

The p-orbitals are “dumbell” shaped. Each orbital contains two electrons, for a total of six

The Shrodinger wave equation predicts the shape of the orbitals.

The five d-orbitals are shaped like this. Each orbital can contain two electrons, for a total of 10 electrons. The transition metals are filling

the d-orbitals.

An orbital in the energy diagram is represented by a horizontal line. On the line we place two arrows, one pointing up and one point down, to represent the two electrons in the orbital.

Orbital

Orbital with one electron

Orbital with two electrons

Electrons, have the same charge and repel each other. How can two electrons coexist in an orbital where they are fairly close together?

Electrons, have a property called spin, which has nothing to do with the electrons spinning. Spin is a magnetic property. Each electron acts like a tiny magnet. Orienting the electrons with opposite spin allows the electrons to occupy the same orbital.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

E n

e r

g y

Electron Energy Diagram for Arsenic

Electrons with opposite spin are represented by up and down arrows.

Each horizontal line represents an orbital, a region which can be occupied by up to two electrons.

The electron energy diagram represents the arrangement of the electrons in their respective energy levels and sublevels.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

E n

e r

g y

Electron Energy Diagram for Arsenic

Hund’s rule says that orbitals at the same energy each get one electron before the second electron is added to an orbital.

Hund’s rule also says that all the electrons in the singly occupied orbitals will have the same spin.

This is why all the arrows in the 4p are in different orbitals and pointed up.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

6s 4f5d

6p7s

5f6d

7p

E n

e r

g

y

Electron Energy Diagram

1s

E n

e r

g

y

Electron Energy Diagram

1s

2s2p

E n

e r

g

y

Electron Energy Diagram

The second energy splits into two sublevels called “s” and “p”. An s-sublevel holds two electons. A p-sublevel holds up to six electrons in three orbitals.

1s

2s2p

3s3p

3d

E n

e r

g

y

Electron Energy Diagram

The third energy splits into three sublevels, the “s”, the “p”, and the “d”. The d-sublevel holds up to ten electrons in five orbitals.

1s

2s2p

3s

4s3p

4p

3d

4d

4f

E n

e r

g

y

Electron Energy Diagram

The fourth energy splits into four sublevels, the “s”, the “p”, the “d”, and the “f ”. The f-sublevel holds up to 14 electrons in seven orbitals.

Notice that the 4s sublevel is lower in energy than the 3d sublevel.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

4f5d

5fE

n e

r g

y

Electron Energy Diagram

Notice the overlap again in the 5s and 4d, and the location of the 4f sublevel.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

6s 4f5d

6p

5f6d

E n

e r

g

y

Electron Energy Diagram

The 6s-sublevel is lower in energy than the 4f sublevel.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

6s 4f5d

6p7s

5f6d

7p

E n

e r

g

y

Electron Energy Diagram

The 7s-sublevel is lower in energy than the 5f sublevel.

The energy sublevels are filled in order from lowest energy to highest energy.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

6s 4f5d

6p7s

5f6d

7p

E n

e r

g

y

The order in which the energy sublevels are filled follows the red line.

Electron Energy Diagram

This is called the Aufbau principle. Aufbau means “building up”, and refers to the building up of the atom one electron at a time.

Periodic table - Sublevels

s pd

f

Order in which the energy sublevels are filled.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

6s 4f5d

6p7s

5f6d

7p

E n

e r

g

y

Electron Energy Diagram

The order in which the orbitals are filled can also be predicted from the graph of ionization energy.

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s

H

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s

He

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s

Li

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s

Be

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p

B

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p

C

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p

N

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p

O

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p

F

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p

Ne

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s

Na

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s

Mg

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p

Al

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p

Si

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p

P

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p

S

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p

Cl

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p

Ar

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s

K

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s

Ca

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

Sc

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

Ti

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

V

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

Cr

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

Mn

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

Fe

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

Co

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

Ni

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

Cu

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d

Zn

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p

Ga

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p

Ge

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p

As

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p

Se

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p

Br

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p

Kr

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p 5s

Rb

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p 5s

Sr

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d

Y

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d

Tc

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d

Cd

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p

In

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p

Sb

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p

Xe

H

He

Li

Ne

Na

Ar

K

Kr

Rb

Xe

Cs

0

500

1,000

1,500

2,000

2,500

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p

Cs

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

E n

e r

g y

Electron Energy Diagram for Arsenic

We can represent the arrangement of electrons more simply by using the “electron configuration.”

1s2, 2s2 2p6, 3s2 3p6, 4s2, 3d10, 4p3

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

E n

e r

g y

Electron Energy Diagram for Arsenic

We can simplify the “electron configuration” even more by using the “inert gas core” to represent the electrons which do not take part in chemical reactions.

1s2, 2s2 2p6, 3s2 3p6, 4s2, 3d10, 4p3

Inert gas core – the inert gas is argon.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

E n

e r

g y

Electron Energy Diagram for Arsenic

We can simplify the “electron configuration” even more by using the “inert gas core” to represent the electrons which do not take part in chemical reactions.

1s2, 2s2 2p6, 3s2 3p6, 4s2, 3d10, 4p3ArWrite the symbol of the inert gas in square brackets.

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

E n

e r

g y

Electron Energy Diagram for Arsenic

Write the electron configuration using the inert gas core for the following elements:1. Al 4. P2. V 5. Sn3. Br 6. Bi

1s2, 2s2 2p6, 3s2 3p6, 4s2, 3d10, 4p3Ar

Write the electron configuration using the inert gas core for the following elements:

1. Al 4. P2. V 5. Sn3. Br 6. Bi

1. [Ne] 3s2 3p1

2. [Ar] 4s2, 3d3

3. [Ar] 4s2, 3d10, 4p5

4. [Ne] 3s2, 3p3

5. [Kr] 5s2, 4d10, 5p2

6. [Xe] 6s2, 4f14, 5d10, 6p3

How many valence electrons does each element have?

Valence electrons are the outer-most electrons which are involved in bonding.

1. [Ne] 3s2 3p1

2. [Ar] 4s2, 3d3

3. [Ar] 4s2, 3d10, 4p5

4. [Ne] 3s2, 3p3

5. [Kr] 5s2, 4d10, 5p2

6. [Xe] 6s2, 4f14, 5d10, 6p3

1. Al 3

The valence electrons have the highest principal quantum number.

1. Al 4. P2. V 5. Sn3. Br 6. Bi

1. [Ne] 3s2 3p1

2. [Ar] 4s2, 3d3

3. [Ar] 4s2, 3d10, 4p5

4. [Ne] 3s2, 3p3

5. [Kr] 5s2, 4d10, 5p2

6. [Xe] 6s2, 4f14, 5d10, 6p3

1. Al 32. V 5

The valence electrons have the highest principal quantum number.

1. Al 4. P2. V 5. Sn3. Br 6. Bi

Some transition metals have their valence electrons in the s and d orbitals.

1. [Ne] 3s2 3p1

2. [Ar] 4s2, 3d3

3. [Ar] 4s2, 3d10, 4p5

4. [Ne] 3s2, 3p3

5. [Kr] 5s2, 4d10, 5p2

6. [Xe] 6s2, 4f14, 5d10, 6p3

1. Al 32. V 5 3. Br 7

The valence electrons have the highest principal quantum number.

1. Al 4. P2. V 5. Sn3. Br 6. Bi

1. [Ne] 3s2 3p1

2. [Ar] 4s2, 3d3

3. [Ar] 4s2, 3d10, 4p5

4. [Ne] 3s2, 3p3

5. [Kr] 5s2, 4d10, 5p2

6. [Xe] 6s2, 4f14, 5d10, 6p3

1. Al 32. V 5 3. Br 74. P 5

The valence electrons have the highest principal quantum number.

1. Al 4. P2. V 5. Sn3. Br 6. Bi

1. [Ne] 3s2 3p1

2. [Ar] 4s2, 3d3

3. [Ar] 4s2, 3d10, 4p5

4. [Ne] 3s2, 3p3

5. [Kr] 5s2, 4d10, 5p2

6. [Xe] 6s2, 4f14, 5d10, 6p3

1. Al 32. V 5 3. Br 74. P 55. Sn 4

The valence electrons have the highest principal quantum number.

1. Al 4. P2. V 5. Sn3. Br 6. Bi

1. [Ne] 3s2 3p1

2. [Ar] 4s2, 3d3

3. [Ar] 4s2, 3d10, 4p5

4. [Ne] 3s2, 3p3

5. [Kr] 5s2, 4d10, 5p2

6. [Xe] 6s2, 4f14, 5d10, 6p3

1. Al 32. V 5 3. Br 74. P 55. Sn 46. Bi 5

The valence electrons have the highest principal quantum number.

1. Al 4. P2. V 5. Sn3. Br 6. Bi

1. [Ne] 3s2 3p1

2. [Ar] 4s2, 3d3

3. [Ar] 4s2, 3d10, 4p5

4. [Ne] 3s2, 3p3

5. [Kr] 5s2, 4d10, 5p2

6. [Xe] 6s2, 4f14, 5d10, 6p3

1. Al 32. V 5 3. Br 74. P 55. Sn 46. Bi 5

Look at the Roman numeral at the top of the column for each element.

The valence electrons have the highest principal quantum number.

Look at the Roman numeral at the top of the column for each element.

1. Al 32. V 5 3. Br 74. P 55. Sn 46. Bi 5

The Roman numeral at the top of each column on the period table tells the number of valence electrons.

Mike JonesPisgah High SchoolCanton NC 28716mjones@haywood.k12.nc.us

+

1s

2s2p

3s

4s3p

4p

3d

4d5s

5p

6s 4f5d

6p7s

5f6d

7p

E n

e r

g

y

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