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Regents Chemistry: Mr. Palermo

Notes: Unit 4: Periodic Table

MIND BLOWN!!!!

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Key Ideas:

x The placement or location of elements on the Periodic Table gives an indication of physical and chemical properties of that element. The elements on the Periodic Table are arranged in order of increasing atomic number. (3.1y)

x Elements can be classified by their properties and located on the Periodic Table as metals, nonmetals, metalloids (B, Si, Ge, As, Sb, Te), and noble gases. (3.1v)

x Elements can be differentiated by their physical properties. Physical properties of substances, such as density, conductivity, malleability, solubility, and hardness, differ among elements. (3.1w)

x Elements can be differentiated by chemical properties. Chemical properties describe how an element behaves during a chemical reaction. (3.1x)

x Some elements exist in two or more forms in the same phase. These forms differ in their molecular or crystal structure, and hence in their properties. (5.2f)

x For Groups 1, 2, and 13-18 on the Periodic Table, elements within the same group have the same number of valence electrons (helium is an exception) and therefore similar chemical properties. (3.1z)

x The succession of elements within the same group demonstrates characteristic trends: differences in atomic radius, ionic radius, electronegativity, first ionization energy, metallic/nonmetallic properties. (3.1aa)

x The succession of elements across the same period demonstrates characteristic trends: differences in atomic radius, ionic radius, electronegativity, first ionization energy, metallic/nonmetallic properties. (3.1bb)

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UNIT 4: PERIODIC TABLE WWW.MRPALERMO.COM

LESSON 4.1 DEVELOPMENT OF THE PERIODIC TABLE

MENDELEEV

•  Organized the elements based upon ATOMIC MASS

MOSLEY

•  Developed the Modern Day Table •  Organized elements by # of PROTONS

(Atomic Number)

PERIODIC LAW

•  The properties of elements are periodic functions of their atomic numbers.

THE RESULT…..

•  Can fill in gaps to predict undiscovered elements and their properties

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HOW IS THE TABLE ORGANIZED?

•  PERIODS (horizontal rows) -  Equal to the # of energy levels (shells)

•  GROUPS (vertical columns) -  elements have the SAME # of VALENCE

ELECTRONS resulting in similar chemical properties

Period � Group �

•  # of period tells us the # of e- SHELLS (AKA principal energy level)

•  properties of elements change

drastically ACROSS A PERIOD (metals ! metalloids/semi-metals ! nonmetals)

•  # of VALENCE ELECTRONS increases

from left to right (1 ! 8) •  Ex: K is in period 4

REACTIVITY OF ELEMENTS

•  Determined by # of valence electrons

•  All atoms (except Hydrogen) want 8 VALENCE ELECTRONS to become STABLE (full valence shell)

•  Called a STABLE OCTET

•  The closer to a stable octet the MORE REACTIVE the element is.

****Period 1 elements need 2 electrons to have a full valence shell NOT 8

EXAMPLE:

Which element is in Group 2 and has 4 energy levels?

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EXAMPLE:

•  Which two elements have similar chemical properties and why? Na, K, Li, Be

•  Na & K are in the same group and have the same number of valence electrons

LESSON 4.2 CATEGORIES & PROPERTIES OF ELEMENTS

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METALS, NONMETALS, METALLOIDS

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

He

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

�

Ω

METALS

Nonmetals

Metalloids

ELEMENT GROUPS

GROUP 1: ALKALINE METALS

•  1 valence electron •  Lose 1 electron to form +1 ions •  Extremely reactive with water •  Most REACTIVE metal is Fr

GROUP 2: ALKALINE EARTH METALS

•  2 valence electrons •  Lose 2 electrons to form +2 ions •  Fairly reactive in water

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GROUPS 3-12: TRANSITION METALS

•  Least reactive metals •  Form COLORED IONS in solution

GROUP 17: HALOGENS

•  7 valence electrons •  Gain 1 electron to for -1 ions •  Most REACTIVE nonmetal is F

GROUP 18: NOBLE GASES

•  Unreactive or INERT •  Stable octet (8 valence electrons) -  Exception is He which has 2 valence

electrons -  monoatomic

HYDROGEN

•  Not officially part of a group •  Nonmetal •  Gas at STP

PROPERTIES OF METALS

•  Malleable (can be hammered or rolled into thin sheets)

•  Ductile (can be drawn into a wire) •  Excellent conductors of heat and electricity •  Luster (shiny) •  Lose electrons to

form cations •  Solid @ STP (except Hg)

METALS HAVE A “SEA” OF MOBILE ELECTRONS….RESULTS IN

ELECTRICAL CONDUCTIVITY

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WHY DO METALS HAVE LUSTER?

•  Metals easily absorb light energy which excites the delocalized electrons and when they fall back to lower energy levels they emit light (luster)

WHY ARE METALS MALLEABLE AND DUCTILE?

•  Metals consist of layers of atoms that can slide over each other

WHY ARE ALLOYS (MIXTURES OF METALS) STRONGER THAN PURE

METALS?

•  Alloys such as brass (a mixture of copper and zinc) are harder than the original metals because the irregularity in the structure helps to stop rows of atoms from slipping over each other

METALLIC CHARACTER

•  How much “like a metal” an element is •  Franicium is most metallic -  Closer to Fr more metallic…further from Fr

least metallic

PROPERTIES OF METALLOIDS

•  Semiconductors (Good/moderate conductor)

•  Luster (like metals) and Brittle (like nommetals)

•  Used for making computer microchips

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PROPERTIES OF NON-METALS

•  Poor conductors of heat and electricity

•  Brittle (shatter when struck) •  Dull •  Tend to gain electrons to form anions

SUMMARY OF THE CATEGORIES OF ELEMENTS

LESSON 4.3 TRENDS IN ATOMIC RADIUS

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ATOMIC RADIUS

•  SIZE of the atom •  Located on Table S

TREND IN ATOMIC RADIUS

ACROSS A PERIOD

•  Trend: DECREASES •  Why? •  Nuclei have greater NUCLEAR PULL

(larger positive charges) which PULL electrons CLOSER

Atomic radius decreases

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13 +

Less nuclear charge Greater nuclear charge

Al

Cl

17 +

DOWN A GROUP

•  Trend: INCREASES •  Why? •  GREATER number of ENERGY SHELLS

(indicated by the PERIOD #)

Ato

mic

Rad

ius

incr

ease

s

USING TABLE “S” TO DETERMINE TRENDS IN ATOMIC RADIUS

TO FIGURE OUT:

•  Pick a Period (row) or Group (column) and note the values of the elements

•  Example: Going across a period what is the trend in atomic radius?

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•  Pick an element on the left side of the periodic table and pick another element on the right side of the same period.

130 pm 60 pm

Trend is decreasing

"

RECALL…..

ION SIZE- METALS

•  Ion radius SMALLER than atomic radius

Why? •  Metal ions LOSE electrons to form Cations

ION SIZE- NONMETALS

•  Ion radius LARGER than atomic radius

•  Why? •  Nonmetal ions GAIN electrons to for

anions.

© 2002 Prentice-Hall, Inc.

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LESSON 4.4 TRENDS IN IONIZATION

ENERGY & ELECTRONEGATIVITY

RECALL……REACTIVITY Metals

•  Decreases across period

•  Increases down group

•  Reason: The larger the atom the weaker the nuclear pull and the more easily you lose electrons and become stable

Non Metals

•  Increases across period

•  Decreases down group

•  Reason: The smaller the atom the greater the nuclear pull (+) and the more easily it attracts electrons (-)

+

+

e-

e-

Larger atom

Smaller atom

IONIZATION ENERGY

•  Energy required to REMOVE the most loosely bound ELECTRON in the valence shell

•  Located on Table S

TREND IN IONIZATION ENERGY

•  INCREASES across a PERIOD •  Why? •  Stronger NUCLEAR PULL makes it more

difficult to remove electrons

13 +

Less nuclear charge Greater nuclear charge

Al

Cl

e-

e-

17 +

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TREND IN IONIZATION ENERGY

•  DECREASES down a GROUP •  Why? •  Larger atomic radius means LESS

NUCLEAR PULL on outer electrons

+

e-

+

e-

EXAMPLE

•  What is trend in atomic radius going down a group?

•  Why does this trend occur?

•  496 •  419 •  403

Trend is decreasing larger atomic radius equals less nuclear pull on valence e-

ELECTRONEGATIVITY

•  Measure of the ATTRACTION for electrons •  Located on Table S

•  FLUORINE most electronegative (4.0) •  The closer an atom is to Fluorine the

HIGHER the electronegativity •  Scale of 0 - 4

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TREND IN ELECTRONEGATIVITY

•  INCREASES across period •  Why? -  Greater NUCLEAR PULL(charge) to attract

electrons 13 +

Less nuclear charge Greater nuclear charge

Al

Cl

e-

e-

17 +

TREND IN ELECTRONEGATIVITY

•  DECREASES down group •  Why? -  Larger atomic radius means LESS

NUCLEAR PULL to attract electrons to the valence shell

+

+

e-

e-

EXAMPLE

a. What is the trend in electronegativity across a period?

b. Why does this trend occur?

The Trend is INCREASING

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Decreases Increases Electronegativity

Decreases Increases Ionization Energy

Increases Decreases Atomic Radius

Increases Decreases Metallic Character

Variation down a Group

Variation across a Period

Periodic Property

Summary