Chapter 2 Periodic Table

7/30/2019 Chapter 2 Periodic Table

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Copyright (c) 1999 by Harcourt Brace & Company All rights reserved

Periodic Table

Inside the Periodic Table


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History of Periodic Table Came from the ideas of many

scientists in the 18 th and 19 th centuries

Observations grouping of properties predictions(hypothesis) of further

experiments theories First introduced by Dmitri

Ivanovitch Mendeleev in 1869


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MendeleevsPeriodic Table

Realized that if elements werearranged in order of increasingatomic mass certain properties

were repeated Arranged the elements in

horizontal rows in order of increasing atomic number

Each time an element had similar properties to one before it, hestarted a new row under that

preceding element


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MendeleevsPeriodic Table

Noticed to leave empty spaces toretain an order of arrangement of similar properties

Realized that there were holes tobe filled by undiscoveredelements

Law of chemical periodicity :properties of the elements areperiodic functions


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H

1

Li7

Be9.4

F19

B11

N14

C12

O16

Si

28

P

31

S

32

Cl

35.5

Mg

24

Na

23

Al

27.3K

39

Ca

40

Mn

55

--

44

V

51

Ti

48

Cr

52

Fe56,Co59

Ni 59,Cu63

Zr

90

Nb

94

Mo

96

--

100

Sr

87

Rb

85

Yt

88

--72

Br 80

Zn65

Cu63

--68

Se78

As75

Ru104,Rh104

Pd105,Ag108

R 2O R 2O6 R 2O7 RO 2 R 2O5 RO R 2O3


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Pb207

Bi208

--Hg200

Au199

Tl204

?Ce140

-- -- --Ba137

Cs133

?Di138

-- -- --?Er

178

Ta

182

?La

180

W

184

--

Th

231

-- U

240

------ --

Os195,Ir197Pt198,Au199

-- -- ---- ---- --

Sn

118

Sb

122

I

127

Cd

112

Ag

108

In

113


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Periodic Table Mosley noticed with electrons in a

cathode ray tube that they emitted

x-rays indicative of their atomic number Realized that the atomic

properties are related to atomicnumber and not atomic mass asMendeleev thought


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Periodic Table

Elements are arranged so thatsimilar properties are in groups

(vertical columns) Main group elements A group Transition elements B groups Periods horizontal rows

(number from 1 starting H and He)


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Periodic Table Divided into regions : metals,

nonmetals, and metalloids Metals malleable, ductile,

conduct electricity Nonmetals do not conduct

electricity Metalloids some properties of

metals and nonmetals (B, Si, Ge,As, Sb, Te)


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Group 1A All called the alkali metals All are metals (except H) Form similar compounds with

oxygen in the form of A 2O Solids at room temp, very reactive

with water


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Group IIA Called alkaline earth elements Composed of all metals Calcium very important element

for our bones


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Transition Elements

All metals Have commercial uses Some are very well known and are

expensive Gold, platinum, silver


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Lanthanides and

Actinides Two last rows of periodic table Some are radioactive


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Group 3A

Aluminum (Al) has many uses All are metals except boron which

is a metalloid Boron is found as borax which is

in many cleaning products


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Group 4A Nonmetal Carbon (C) Metalloids silicon (Si) and

germanium (Ge) Metals tin (Sn) and lead (Pb) By far C is the most important

element in this Group


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Carbon Allotropes element can exist in

several different and very distinct

forms Graphite and diamonds


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Group 5A and 6A

Most important elements arenitrogen (N) in 5A and oxygen (O)

in 6A Sulfur has been known since

ancient times as burning stone


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Group 7A Referred to as Halogens F, Cl, Br, I exist as diatomic

molecules (i.e. F 2, Cl 2, etc)


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Copyright (c) 1999 by Harcourt Brace & CompanyAll rights reserved

Group 8A

Noble gases it was originallybelieved that none of these gases

would react with other elements Sometimes called inert gases or

rare gases

He, Ne, Ar, Kr, Xe

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Chapter 2 Periodic Table