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Periodic Table. Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 74. History of the Periodic Table. Dmitri Mendeleev. Russian - 1872 Invented periodic table Organized elements by properties Arranged elements by atomic mass Predicted existence of several unknown elements

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periodic table

Periodic Table

Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 74

dmitri mendeleev
Dmitri Mendeleev
  • Russian - 1872
  • Invented periodic table
  • Organized elements by properties
  • Arranged elements by atomic mass
  • Predicted existence of several unknown elements
  • Element 101

Dmitri Mendeleev

dmitri mendeleyev 1834 1907
Dmitri Mendeleyev (1834-1907)
  • observed that elements listed in order of atomic mass showed regularly (or periodically) repeating properties.
  • He announced his Periodic Law in 1869 and published a list of known elements in a tabular form.
  • He had the courage to leave gaps where the Periodic Law did not seen to fit, predicting that new elements would be discovered to fill them.
modern periodic table
Modern Periodic Table
  • H.G.J. Moseley
  • Arranged elements by increasing atomic number
  • Killed in WW I at age 28

(Battle of Gallipoli)

1887 - 1915

periodic law
Periodic Law
  • “When elements are arranged in order of increasing atomic number, their physical and chemical properties show a PERIODIC pattern”
organization of the table
Organization of the Table
  • Elements that have similar properties are aligned in vertical columns called GROUPS or FAMILIES.
  • Elements of increasing atomic numbers are arranged in horizontal rows called PERIODS.
groups
Groups
  • All elements in a group have the same number of valence electrons (outermost)
  • All elements in a group have similar chemical properties
  • Increase in the metallic properties from top to bottom
slide10
Group 1 – Alkali Metals

Metallic Properties

Tarnish rapidly

Easily forms +1 ions

Soft enough to cut with a knife

EXTREMELY reactive (air)

Valence configuration of s1

Group 2 - Alkaline Earth

Metallic properties

Form +2 ions

Higher densities and melting points of group 1

Valence configuration of s2

potassium metal in water
Potassium Metal in Water

Newmark, CHEMISTRY, 1993, page 25

slide12
Group 17 (VIIA)

Halogens

Very Reactive

Various Ions but usually -1

Valence configuration is s2p5

Group 18 (VIIIA)

Noble Gases

Very UNreactive

Called the inert, rare gases, monatomic gases

Valence configuration is s2p6

transition elements
Transition Elements
  • D-block elements
  • Have several empty or half filled d orbitals
  • Multiple oxidation states because the d orbital values are close to those of s orbital values and different electrons can be removed
  • Form colored solutions
  • Most have high density and high melting points
metals and nonmetals
MetalloidsMetals and Nonmetals

H

1

He

2

1

Li

3

Be

4

B

5

C

6

N

7

O

8

F

9

Ne

10

Nonmetals

2

Na

11

Mg

12

Al

13

Si

14

P

15

S

16

Cl

17

Ar

18

3

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

4

METALS

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

5

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

*

6

Fr

87

Ra

88

Rf

104

Db

105

Sg

106

Bh

107

Hs

108

Mt

109

W

7

La

57

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

Ac

89

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

metals vs non metals
2/3 of all elements

Have luster

Good conductors of heat and electricity

Solid at room temp. (except Hg)

Malleable

Ductile

Tend to LOSE electrons

Poor conductors of heat and electricity (insulators)

No luster

Not malleable or ductile (brittle)

Gaseous, liquid or solid

Tend to gain or share electrons.

Metals Vs Non-Metals
semimetals metalloid
Semimetals/metalloid
  • On the stepline
  • Could have a combination of metal and nonmetal properties
  • Considered the natural change in character of elements as you go across the period
  • Only 7 elements
slide18
metallic character increases

nonmetallic character increases

metallic character increases

nonmetallic character increases

solids liquids and gases
Solids, Liquids, and Gases
  • Most elements are solids.
  • Two liquids on the periodic table: Mercury (Hg) is a metal and Bromine (Br) is a nonmetal.
  • Ten gases on the periodic table: H2, He, N2, O2, F2, Cl2, Ne, Ar, Kr, Xe, Rn
diatomic molecules
Diatomic Molecules

BrINCLHOF twins

H2O2Br2F2I2N2Cl2

ionization energy
Ionization Energy
  • The energy needed to remove one of an atom’s electrons.
  • The greater the shielding effect; the easier to remove an electron.
shielding effect
Shielding Effect

Valence

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

+

-

-

nucleus

-

Electrons

-

Electron

Shield

“kernel”

electrons

slide24
He

Ne

Ar

Kr

H

Li

Na

K

Rb

First Ionization energy

Atomic number

electronegativity
Electronegativity
  • the ability to attraction electrons in a bond
  • based on 0-4 scale
  • Which element has the highest? the lowest?
  • Fluorine and Francium
explanation of the trend
Explanation of the trend

Electronegativity decreases down a group.

  • atomic radius increases
  • outer electrons are shielded from the attraction of the nucleus
  • bonding electrons are less strongly attracted to nucleus
explanation of the trend30
Explanation of the Trend

Electronegativity increases across a period

  • nuclear charge increases
  • atomic radius decreases
  • shielding is negligible because same energy level
  • bonding electrons more strongly attracted to the nucleus
atomic radius
Atomic Radius
  • The distance from the center of the atom’s nucleus to the outer edge of the outermost electron.
periodic trends in atomic radii
Periodic Trends in Atomic Radii

LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 175

atomic radius summary
Atomic Radius - Summary
  • Across a period, radius decreases because there is a greater pull on the electrons from the nucleus.
  • Down a period, radius increases because additional energy level is added.
relative size of atoms
Relative Size of Atoms

Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 350

ionic size
Ionic Size
  • Cations form by losing electrons.
  • Cations are smaller than the atom they come from.
  • Metals form cations.
  • Cations of representative elements have noble gas configuration.
slide36
e

e

Li

Li+

Li

152

60

Li+

152

152

60

Lithium atom

Energy

e

e

Li

Li

+

e

Lithium ion

Lithium atom

ionic size37
Ionic size
  • Anions form by gaining electrons.
  • Anions are bigger that the atom they come from.
  • Nonmetals form anions.
  • Anions of representative elements have noble gas configuration.
trends in atomic and ionic size
Group 3A

e

e

e

e

e

e

e

e

e

Li

Li+

152

Na

Na+

Al

50

95

143

186

K

K+

133

227

Trends in Atomic and Ionic Size

Metals

Nonmetals

Group 1A

Group 3A

F-

F

64

60

136

Cl-

Cl

99

181

Br-

Br

114

195

Cations are smaller than parent atoms

Anions are larger than parent atoms

summary of periodic trends
Summary of Periodic Trends

Shielding is constant

Atomic radius decreases

Ionization energy increases

Electronegativity increases

Nuclear charge increases

1A

0

Nuclear charge increases

Shielding increases

Atomic radius increases

Ionic size increases

Ionization energy decreases

Electronegativity decreases

2A

3A

4A

6A

7A

5A

Ionic size (cations) Ionic size (anions)

decreases decreases

how to measure
How to measure

What is the size of the paper?

How many decimal places should the answer have?

more measurement
More Measurement

How tall is the plant to the correct number of decimal places?

metric system
Metric System

k – h – da – base – d – c - m

accuracy vs precision
Accuracy vs. Precision

Accuracy – how close the measurement is to a “true value”

Precision - how close several measurements are to each other

significant figures
Significant Figures

The A & P rule:

Decimal absent : Atlantic Side and count across the country.

Decimal present : Pacific Side and count across the country.

significant figures practice
How many sig figs present?

37400

300.0

0.0045

Round each to two significant digits.

349987

0.3445

Significant Figures Practice
significant figures and calculations
Significant Figures and Calculations
  • For + and -; reduce answer to least number of decimal places in the problems
  • For x and ; reduce answer to least number of significant figures in the problem.
sig fig calculation practice
345.1 + 27. 35

99.456 - 34

435.2 x 76.1

150 / 4

Sig Fig Calculation Practice
density
Density

ratio of mass to volume

D = m/v on reference table T

density is not size dependent.

What is the density of a 3 cm cube that

weighs 27 g?

percent error
Percent Error

used to analyze lab data

closeness the “true value”

observed – accepted  x 100 on table T

accepted

If a student calculates the mass of Ne to be 19.9 g and the true value is 20.2 g; what is the percent error?

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