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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 l.jpg

Periodic Table

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



Dmitri mendeleev l.jpg
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 l.jpg
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 l.jpg
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


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Periodic Law

  • “When elements are arranged in order of increasing atomic number, their physical and chemical properties show a PERIODIC pattern”


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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.


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Groups of Elements


Groups l.jpg
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


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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


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Potassium Metal in Water

Newmark, CHEMISTRY, 1993, page 25


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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 l.jpg
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 l.jpg

Metalloids

Metals 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


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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 l.jpg
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 l.jpg

metallic character increases

nonmetallic character increases

metallic character increases

nonmetallic character increases


Solids liquids and gases l.jpg
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 l.jpg
Diatomic Molecules

BrINCLHOF twins

H2O2Br2F2I2N2Cl2



Ionization energy l.jpg
Ionization Energy

  • The energy needed to remove one of an atom’s electrons.

  • The greater the shielding effect; the easier to remove an electron.


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Shielding Effect

Valence

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

+

-

-

nucleus

-

Electrons

-

Electron

Shield

“kernel”

electrons


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He

Ne

Ar

Kr

H

Li

Na

K

Rb

First Ionization energy

Atomic number


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Electronegativity

  • the ability to attraction electrons in a bond

  • based on 0-4 scale

  • Which element has the highest? the lowest?

  • Fluorine and Francium



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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



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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 l.jpg
Atomic Radius

  • The distance from the center of the atom’s nucleus to the outer edge of the outermost electron.


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Periodic Trends in Atomic Radii

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


Atomic radius summary l.jpg
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.


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Relative Size of Atoms

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


Ionic size l.jpg
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 l.jpg

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 l.jpg
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 l.jpg

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 l.jpg
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 l.jpg
How to measure

What is the size of the paper?

How many decimal places should the answer have?


More measurement l.jpg
More Measurement

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


Metric system l.jpg
Metric System

k – h – da – base – d – c - m


Accuracy vs precision l.jpg
Accuracy vs. Precision

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

Precision - how close several measurements are to each other


Significant figures l.jpg
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 l.jpg

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 l.jpg
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 l.jpg

345.1 + 27. 35

99.456 - 34

435.2 x 76.1

150 / 4

Sig Fig Calculation Practice


Density l.jpg
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 l.jpg
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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