The Periodic Table

(very) Brief History• 1869 Mendeleev* & Meyer published similar

tables*First to be recognized at international convention

– Elements were ordered based on atomic mass

• Henry Moseley developed the atomic # concept– Proved more accurate than Mendeleev’s atomic mass

method

The Periodic Law

• When elements are arranged by increasing atomic # their chemical & physical properties show a periodic pattern.

Review of Element Symbol

• Atomic #– #protons

• Element Symbol• Atomic Mass

– Weighted average of all isotopes’ mass #

– Listed in AMUs– Equal to MM (g/mol)

• Element Name

54.938049 54.938049

Periodic Table Layout

• Groups or Families– Columns, Vertical– 18 groups

• Periods– Rows, Horizontal– 7 periods

• Kinds of Elements– Metals, Nonmetals, Semi-metals– Varying Properties

Groups to know– Group 1 - Alkali Metals– Group 2 - Alkaline Earth Metals– Group 17 Halogens– Group 18 - Noble Gases

Electron ConfigurationsUsing the Periodic Table

1IA

11

H1.00797

2IIA

23

Li6.939

4Be

9.0122

311

Na22.9898

12Mg

24.305

419K

39.102

20Ca

40.08

537

Rb85.47

38Sr

87.62

655

Cs132.905

56Ba

137.34

787Fr

[223]

88Ra[226]

s-block elements:

Group 1: Alkali

H - 1s1

Li - 1s22s1

Na- 1s22s22p63s1

K - 1s22s22p63s23p64s1

s-block elements:

Group 2: Alkaline Earth

Be - 1s22s2

Mg- 1s22s22p63s2

Ca - 1s22s22p63s23p64s2

Electron Configurations (con’t)

p-block elements:

Group 13: B -1s22s22p1

Group 14: Si -1s22s22p63s23p2

Group 15: As-1s22s22p63s23p64s23d104p3

Group 16: S -

1s22s22p63s23p4

Group 17: Br- 1s22s22p63s23p64s23d104p5

18VIIIA

13IIIA

14IVA

15VA

16VIA

17VIIA

2He

4.00265B

10.811

6C

12.0112

7N

14.0067

8O

15.9994

9F

18.9984

10Ne

20.17913Al

26.9815

14Si

28.086

15P

30.9738

16S

32.064

17Cl

35.453

18Ar

39.948

7

31Ga65.37

32Ge72.59

33As

74.9216

34Se78.96

35Br

79.909

36Kr

83.80

40

49In

114.82

50Sn

118.69

51Sb

121.75

52Te

127.60

53I

126.904

54Xe

131.30

59

81Tl

204.37

82Pb

207.19

83Bi

208.980

84Po[210]

85At

[210]

86Rn[222]

Noble Gas Configuration

Choose Noble Gas Prior to ElementFOCUS ON THE VALENCE SHELL

Put Noble gas in brackets,ex. [Ne]

This represents the “inner shell” of the element

Add the outer level electrons by row # (2-7) s & p

**d level starts on 4th row**4f & 5f start on 6th & 7th row

Examples:

Ni: [Ar] 4s23d8 **remember that 3d fills after 4s and before 4p

Sb: [Kr] 5s24d105p3

Trends in the Periodic TableDefinition: Predictable changes in properties of the elements as you move through the table. (Realize there are exceptions)

1 1H

2 3Li

4Be

3 11Na

12Mg

4 19K

20Ca

5 37Rb

38Sr

6 55Cs

56Ba

7 87Fr

88Ra

21Sc

22Ti

23V

24Cr

25Mn

26Fe

27Co

28Ni

29Cu

30Zn

39Y

40Zr

41Nb

42Mo

43Tc

44Ru

45Rh

46Pd

47Ag

48Cd

57La

72Hf

73Ta

74W

75Re

76Os

77Ir

78Pt

79Au

80Hg

89Ac

104Rf

105 106 107 108 109

2He

5B

6C

7N

8O

9F

10Ne

13Al

14Si

15P

16S

17Cl

18Ar

31Ga

32Ge

33As

34Se

35Br

36Kr

49In

50Sn

51Sb

52Te

53I

54Xe

81Tl

82Pb

83Bi

84Po

85At

86Rn

Db Hs MtSg Bh

Ionic Size+Ions are Smaller

- Ions are larger

Atomic Radii Decrease

Incr

eas

e

Ionization EnergyIncrease

Dec

reas

e

Atomic Radii - distance from the nucleus to outermost electron.

Ionization Energy - energy required to remove an electron (kJ/mol)

Electron Affinity – energy change when neutral atom gains electron

Electron AffinityIncrease

Dec

reas

e

Ionization Energy• In general, ionization energies of the main-group

elements increase across each period.

• This increase is caused by increasing nuclear charge.

• A higher charge more strongly attracts electrons in the same energy level.

• Among the main-group elements, ionization energies generally decrease down the groups.

• Electrons removed from atoms of each succeeding element in a group are in higher energy levels, farther from the nucleus.(electron shielding)

• The electrons are removed more easily.

Additional Trend Information

Electron AffinityThe energy associated with an atom gaining or losing an

electron. (kJ/mol)• + Energy means it requires energy …not favorable

• - Energy means it gives up energy…favorable

• ElectronegativityThe ability to attract an electron during bonding

• Increases up a group and across a period

Electron Affinity

• The energy change that occurs when an electron is acquired by a neutral atom is called the atom’s electron affinity.

• Electron affinity generally increases across periods.• Increasing nuclear charge along the same

sublevel attracts electrons more strongly

• Electron affinity generally decreases down groups.• The larger an atom’s electron cloud is, the farther

away its outer electrons are from its nucleus.

Ionic Radii• A positive ion is known as a cation.

• The formation of a cation by the loss of one or more electrons always leads to a decrease in atomic radius.

• The electron cloud becomes smaller. • The remaining electrons are drawn closer to the nucleus by its

unbalanced positive charge.

• A negative ion is known as an anion.

• The formation of an anion by the addition of one or more electrons always leads to an increase in atomic radius.

Ionic Radii, continued• Cationic and anionic radii decrease across a period.

• The electron cloud shrinks due to the increasing nuclear charge acting on the electrons in the same main energy level.

• The outer electrons in both cations and anions are in higher energy levels as one reads down a group.

• There is a gradual increase of ionic radii down a group.

Electronegativity• Valence electrons hold atoms together in chemical

compounds.

• In many compounds, the negative charge of the valence electrons is concentrated closer to one atom than to another.

• Electronegativity is a measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound.

• Electronegativities tend to increase across periods, and decrease or remain about the same down a group.

The Periodic Table

(very) Brief History

• 1800’s - Dobereiner introduced “Triads”– 3 elements with similar properties

• 1865 - Newlands introduced “Law of Octaves”– At this time 62 known elements– 1st behaved like 8th, 2nd like 9th…

• 1869 Mendeleev* & Meyer published similar tables*First to be recognized at international convention

– Elements were ordered based on atomic mass

The Periodic Law

• When elements are arranged by increasing atomic # their chemical & physical properties show a periodic pattern.

1913 - Henry Moseley developed the atomic # concept.– Proved more accurate than Mendeleev’s atomic mass method

Review of Element Symbol

• Atomic #– #protons

• Element Symbol• Atomic Mass

– Weighted average of all isotopes’ mass #

– Listed in AMUs

– Equal to MM (g/mol)

• Element Name

54.938049

Periodic Table Layout• Groups or Families

– Columns, Vertical

– 18 groups

• Periods– Rows, Horizontal

– 7 periods

• Kinds of Elements– Metals, Nonmetals, Semi-metals

– Varying Properties

Groups to know– Group 1 - Alkali Metals– Group 2 - Alkaline Earth Metals– Group 17 Halogens– Group 18 - Noble Gases

Electron ConfigurationsUsing the Periodic Table

1IA

11

H1.00797

2IIA

23

Li6.939

4Be

9.0122

311

Na22.9898

12Mg24.305

419K

39.102

20Ca40.08

537

Rb85.47

38Sr

87.62

655

Cs132.905

56Ba

137.34

787Fr[223]

88Ra[226]

s-block elements:

Group 1: Alkali

H - 1s1

Li - 1s22s1

Na- 1s22s22p63s1

K - 1s22s22p63s23p64s1

s-block elements:

Group 2: Alkaline Earth

Be - 1s22s2

Mg- 1s22s22p63s2

Ca - 1s22s22p63s23p64s2

Electron Configurations (con’t)

p-block elements:

Group 13: B -1s22s22p1

Group 14: Si -1s22s22p63s23p2

Group 15: As-1s22s22p63s23p64s23d104p3

Group 16: S -

1s22s22p63s23p4

Group 17: Br-

1s22s22p63s23p64s23d104p5

18VIIIA

13IIIA

14IVA

15VA

16VIA

17VIIA

2He

4.00265B

10.811

6C

12.0112

7N

14.0067

8O

15.9994

9F

18.9984

10Ne

20.179

13Al

26.9815

14Si

28.086

15P

30.9738

16S

32.064

17Cl

35.453

18Ar

39.948

7

31Ga65.37

32Ge72.59

33As

74.9216

34Se78.96

35Br

79.909

36Kr83.80

40

49In

114.82

50Sn

118.69

51Sb

121.75

52Te

127.60

53I

126.904

54Xe

131.30

59

81Tl

204.37

82Pb

207.19

83Bi

208.980

84Po[210]

85At[210]

86Rn[222]

Noble Gas Configuration

Choose Noble Gas Prior to ElementFOCUS ON THE VALENCE SHELL

Put Noble gas in brackets,ex. [Ne]

This represents the “inner shell” of the element

Add the outer level electrons by row # (2-7) s & p

**d level starts on 4th row**4f & 5f start on 6th & 7th row

Examples:

Ni: [Ar] 4s23d8 **remember that 3d fills after 4s and before 4p

Sb: [Kr] 5s24d105p3

Trends in the Periodic TableDefinition: Predictable changes in properties of the elements as you move through the table.

1 1H

2 3Li

4Be

3 11Na

12Mg

4 19K

20Ca

5 37Rb

38Sr

6 55Cs

56Ba

7 87Fr

88Ra

21Sc

22Ti

23V

24Cr

25Mn

26Fe

27Co

28Ni

29Cu

30Zn

39Y

40Zr

41Nb

42Mo

43Tc

44Ru

45Rh

46Pd

47Ag

48Cd

57La

72Hf

73Ta

74W

75Re

76Os

77Ir

78Pt

79Au

80Hg

89Ac

104Rf

105 106 107 108 109

2He

5B

6C

7N

8O

9F

10Ne

13Al

14Si

15P

16S

17Cl

18Ar

31Ga

32Ge

33As

34Se

35Br

36Kr

49In

50Sn

51Sb

52Te

53I

54Xe

81Tl

82Pb

83Bi

84Po

85At

86Rn

Db Hs MtSg Bh

Ionic Size

+Ions are Smaller

- Ions are larger

Atomic Radii Decrease

Incr

ease

Ionization EnergyIncrease

Dec

reas

e

Atomic Radii - distance from the nucleus to outermost electron.

Ionization Energy - energy required to remove an electron (kJ/mol)

Additional Trend Information

Electron AffinityThe energy associated with an atom gaining or losing an

electron. (kJ/mol)• + Energy means it requires energy …not favorable

• - Energy means it gives up energy…favorable

• ElectronegativityThe ability to attract an electron during bonding

• Increases up a group and across a period