Periodic Table

Dmitri Mendeleev

• Russian chemist• Organized elements by properties

• Arranged elements by atomic mass

• Predicted existence of several unknown elements

• Element 101 - Mendeleevium (Md)

Dmitri Mendeleev

Mendeleev’s Periodic Table

Period Period

11

Group IGroup I IIII IIIIII IVIV VV VIVI VIIVII VIIIVIII

H = 1

22 Li = 7 Be= 9.4 B = 11 C = 12 N = 14 O = 16 F = 19

33 Na = 23 Mg = 24 Al = 27.3 Si = 28 P = 31 S = 32 Cl = 35.5

44 K = 39 Ca = 40 ? = 44 Ti = 48 V = 51 Cr = 52 Mn = 55Fe =56, Co = 59,

Ni = 59

55 Cu = 63 Zn = 65 ? = 68 ? = 72 As = 75 Se = 78 Br = 80

66 Rb = 85 Sr = 87 ? Yt = 88 Zr = 90 Nb = 94 Mo = 96 ? = 100 Ru= 104, Rh = 104, Pd = 106

77 Ag = 108 Cd = 112 In = 113 Sn = 118 Sb = 122 Te = 125 I = 127

88 Cs = 133 Ba = 137 ?Di = 138 ?Ce = 140

99

1010 ?Er = 178 ?La = 180 Ta = 182 W = 184Os = 195, Ir = 197,

Pt = 198

1111 Au = 199 Hg = 200 Tl = 204 Pb = 207 Bi = 208

1212 Th = 231 U = 240

Elements Properties are PredictedProperty Mendeleev’s Predictions in 1871 Observed Properties

Molar Mass

Oxide formula

Density of oxide

Solubility of oxide

Scandium (Discovered in 1877)44 g

M2O3

3.5 g / ml

Dissolves in acids

43.7 g

Sc2O3

3.86 g / ml

Dissolves in acids

Molar mass

Density of metal

Melting temperature

Oxide formula

Solubility of oxide

Gallium (Discovered in 1875)68 g

6.0 g / ml

Low

M2O3

Dissolves in ammonia solution

69.4 g

5.96 g / ml

30 0C

Ga2O3

Dissolves in ammonia

Molar mass

Density of metal

Color of metal

Melting temperature

Oxide formula

Density of oxide

Chloride formula

Density of chloride

Boiling temperature

of chloride

Germanium (Discovered in 1886)72 g

5.5 g / ml

Dark gray

High

MO2

4.7 g / ml

MCl4

1.9 g / ml

Below 100 oC

71.9 g

5.47 g / ml

Grayish, white

900 0C

GeO2

4.70 g / ml

GeCl4

1.89 g / ml

86 0C

Modern Periodic Table

• Based on Mendeleev’s system

• Arrange elements by atomic number

• Elements organized by properties

• Columns are groups or families(1 to 18)

• Rows are periods (1 to 7) showing the variation of chemical and physical properties.

Groups of Elements

1

2

3

4

5

6

7

Li

3

He

2

C

6

N

7

O

8

F

9

Ne

10

Na

11

B

5

Be

4

H

1

Al

13

Si

14

P

15

S

16

Cl

17

Ar

18

K

19

Ca

20

Sc

21

Ti

22

V

23

Cr

24

Mn

25

Fe

26

Co

27

Ni

28

Cu

29

Zn

30

Ga

31

Ge

32

As

33

Se

34

Br

35

Kr

36

Rb

37

Sr

38

Y

39

Zr

40

Nb

41

Mo

42

Tc

43

Ru

44

Rh

45

Pd

46

Ag

47

Cd

48

In

49

Sn

50

Sb

51

Te

52

I

53

Xe

54

Cs

55

Ba

56

Hf

72

Ta

73

W

74

Re

75

Os

76

Ir

77

Pt

78

Au

79

Hg

80

Tl

81

Pb

82

Bi

83

Po

84

At

85

Rn

86

Fr

87

Ra

88

Rf

104

Db

105

Sg

106

Bh

107

Hs

108

Mt

109

Mg

12

Ce

58

Pr

59

Nd

60

Pm

61

Sm

62

Eu

63

Gd

64

Tb

65

Dy

66

Ho

67

Er

68

Tm

69

Yb

70

Lu

71

Th

90

Pa

91

U

92

Np

93

Pu

94

Am

95

Cm

96

Bk

97

Cf

98

Es

99

Fm

100

Md

101

No

102

Lr

103

La

57

Ac

89

1

2

3

4

5

6

7

1A

2A

1A

2A

3A

4A

5A

6A

7A

8A

Alkali metals

Alkali earth metals

Transition metals

Inner transition metals

Boron group

Carbon group

Nitrogen group

Oxygen group

Halogens

Noble gases

Hydrogen

3B 5B 6B 7B 8B 1B 2B

3A 4A 5A 6A 7A

8A

4B

Metals and Nonmetals

Li

3

He

2

C

6

N

7

O

8

F

9

Ne

10

Na

11

B

5

Be

4

H

1

Al

13

Si

14

P

15

S

16

Cl

17

Ar

18

K

19

Ca

20

Sc

21

Ti

22

V

23

Cr

24

Mn

25

Fe

26

Co

27

Ni

28

Cu

29

Zn

30

Ga

31

Ge

32

As

33

Se

34

Br

35

Kr

36

Rb

37

Sr

38

Y

39

Zr

40

Nb

41

Mo

42

Tc

43

Ru

44

Rh

45

Pd

46

Ag

47

Cd

48

In

49

Sn

50

Sb

51

Te

52

I

53

Xe

54

Cs

55

Ba

56

Hf

72

Ta

73

W

74

Re

75

Os

76

Ir

77

Pt

78

Au

79

Hg

80

Tl

81

Pb

82

Bi

83

Po

84

At

85

Rn

86

Fr

87

Ra

88

Rf

104

Db

105

Sg

106

Bh

107

Hs

108

Mt

109

Mg

12

Ce

58

Pr

59

Nd

60

Pm

61

Sm

62

Eu

63

Gd

64

Tb

65

Dy

66

Ho

67

Er

68

Tm

69

Yb

70

Lu

71

Th

90

Pa

91

U

92

Np

93

Pu

94

Am

95

Cm

96

Bk

97

Cf

98

Es

99

Fm

100

Md

101

No

102

Lr

103

La

57

Ac

89

1

2

3

4

5

6

7

METALS

Nonmetals

Metalloids

Properties of Metals, Nonmetals, and Metalloids

METALS malleable, lustrous, ductile, good conductors of heat and electricity

NONMETALSgases or brittle solids at room temperature, poor

conductors of heat and electricity (insulators)

METALLOIDS (Semi-metals)dull, brittle, semi-conductors (used in computer chips)

exhibit properties of both metals and nonmetals

Electrons filling the orbitals shown in the Periodic Table

1s

2s

3s

4s

5s

6s

7s

3d

4d

5d

6d

2p

3p

4p

5p

6p

1s

La

Ac

1

3 4 5 6 7

4f

5f

Lanthanide series

Actinide series

Groups 8

Per

iods

1 2

2

3

4

5

6

7

Size of Atoms - Trends

Periodic Trends in Atomic Radii

Relative Size of Atoms

Shielding Effect

Kernel electrons block the attractive force of the nucleus from the valence electrons

+nucleus

Valence

Electrons--

--

Electron

Shield

“kernel”

electrons

Atomic Radius vs. Atomic NumberRadii vs atomic # up to 53

0.05

0.07

0.09

0.11

0.13

0.15

0.17

0.19

0.21

0.23

3 4 5 6 7 8 9 11 12 13 14 15 16 17 19 20 31 32 33 34 35 37 38 49 50 51 52

Atomic #

Ra

dii

(no

no

me

ters

)

Atomic Radii trend explained• As you go across the period the number of shielding electrons are the

same.• The nuclear charge is increasing (adding protons as you go across).• The electrons added are in the same valence shell – same distance

from the nucleus.• More + nuclear charge gets out to the valence electrons, pulling the

valence electrons in closer (stronger attraction).

As we go down a group each atom has another energy level, so the atoms get bigger.There are more levels in the kernel and therefore greater shielding of valence electrons (weaker attraction).

LiNe

Li

Cs

Why do elements react?

• Atoms with filled valence shells are stable – low in energy. Atoms attain a full valence shell by losing, gaining or sharing valence electrons. The result is a particle which is isoelectronic with a noble gas (has the same electron configuration as a noble gas).

• Na 1+ =1s2 2s2 2p6 (isoelectronic Ne).• F1- = 1s2 2s2 2p6

Atomic and Ionic Radii vs Atomic Number

Radii period trends explained• Metals are “born losers”, the atoms lose their valence

electrons to form cations (+ ions). The kernel is smaller. The remaining electrons are more strongly attracted to the nucleus. There are more protons than electrons so the remaining electrons are pulled in closer (+ ion is smaller).

• Nonmetals will gain valence electrons to fill the valence shell to form anions (- ions). There are more electrons to share the nuclear charge so there is a weaker attraction between the electrons and the nucleus. The weaker attraction leads to the valence electrons being further away (- ion is larger)

Li1+

Be2+

B3+

C4+

N 3 -

O 2 - F 1 -

Radii group trends explained

Li+1

Na+1

K+1

Rb+1

Cs+1

• As you go down the group you are adding energy levels so the cations and anions get bigger.

First Ionization Energy Plot

First ionization energy trend explained• 1st ionization energy is the energy required to

remove one electron from the gaseous atom of an element.

• 1st ionization energy is increased by strong attraction to valence electrons and a stable electron configuration.

• As you go across the period the attraction to valence electrons increases so ionization energy increases.

• Peaks in energy occur at Be (full s sublevel), N (½ full p sublevel) and Ne (full s & p sublevels –full valence shell).

Electronegativity values• Electronegativity is the tendency for an atom to attract electrons to

itself when it is chemically combined with another element.• Big electronegativity values means the atom pulls the valence

electrons toward the nucleus, strong attraction to valence electrons.• Atoms with small electronegativity values have weak attraction to

valence electrons and these electrons are drawn away from this atom.

2.1H

                               

1.0Li

1.5Be

                   2.0B

2.5C

3.0N

3.5O

4.0F

1.0Na

1.2Mg

                   1.5Al

1.8Si

2.1P

2.5S

3.0Cl

0.9K

1.0Ca

1.3Sc

1.4Ti

1.5V

1.6Cr

1.6Mn

1.7Fe

1.7Co

1.8Ni

1.8Cu

1.6Zn

1.7Ga

1.9Ge

2.1As

2.4Se

2.8Br

0.9Rb

1.0Sr

1.2Y

1.3Zr

1.5Nb

1.6Mo

1.7Tc

1.8Ru

1.8Rh

1.8Pd

1.6Ag

1.6Cd

1.6In

1.8Sn

1.9Sb

2.1Te

2.5I

0.8Cs

1.0Ba

1.1La

1.3Hf

1.4Ta

1.5W

1.7Re

1.9Os

1.9Ir

1.8Pt

1.9Au

1.7Hg

1.6Tl

1.7Pb

1.8Bi

1.9Po

2.1At

 

Electronegativity tend explained• Group Trend: The further down a group the

farther the electron is away and the more shielding electrons an atom has – the lower the electronegativity value.

Period Trend: Metals on the left lose electrons easily (weak attraction for valence electrons). Metals have low electronegativity values.

• Nonmetals on the right need more electrons to complete the valence shell and have strong attraction for valence electrons. Nonmetals have high electronegativity values.

• Electronegativity values increase as you go across the period

Electron Affinity values

• Electron Affinity is the energy change associated with adding an electron to a gaseous atom.

• If the atom becomes more stable (electron configuration like the noble gases) there is a loss of energy and the energy change is shown a negative value.

• If the atom becomes less stable the energy level goes up and the energy change is shown as a positive value.

H -73   /          

Li -60 Be +240 \ B -27 C -122 N +9 O -141 F -328

Na -53 Mg +230 / Al -44 Si -134 P -72 S -200 Cl -348

K -48 Ca +156 \ Ga -30 Ge -120 As -77 Se -195 Br -325

Rb -47 Sr +170 / In -30 Sn -121 Sb -101 Te -190 I -295

Cs -45 Ba +52 \ Tl -30 Pb -110 Bi -110 Po -183 At -270

 

Electron Affinity tend explained

• Across a period the electron affinity is low for metals and high for nonmetals (electron affinity increases from left to right). In Group 7A valence electrons are strongly attracted to the nucleus and an extra electron gives the atom a full valence shell.

• Electron affinity decreases as we go down a group because the atoms are getting bigger and the valence electrons are not attracted as strongly to the nucleus.

Summary of Periodic Trends

Ionic size (cations) Ionic size (anions)decreases decreases

Nuclear charge increasesShielding is constantAtomic radius decreasesIonization energy increasesElectronegativity increasesElectron affinity increases

Nu

clea

r ch

arg

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crea

ses

Sh

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in

crea

ses

Ato

mic

rad

ius

incr

ease

sIo

nic

siz

e in

crea

ses

Ion

izat

ion

en

erg

y d

ecre

ases

Ele

ctro

neg

ativ

ity

dec

reas

esE

lect

ron

aff

init

y d

ecre

ase

s

1A 2A

3A 4A 5A 6A 7A

0