How the Periodic Table is

Organized!

Thank you Dmitry Ivanovich

Mendeleyev!!!

Elements as Building Blocks

As you probably saw, the periodic table is organized like a big grid. The

elements are placed in specific locations because of the way they look and

act. If you have ever looked at a grid, you know that there are rows (left to

right) and columns (up and down). The periodic table has rows and

columns, and they each mean something different.

Periodic Table and the Elements

You’ve Got Your Periods… Even though they skip some squares in between, all of the

rows go left to right. When you look at a periodic table, each

of the rows is considered to be a different period (Get it?

Like PERIODic table.). In the periodic table, elements have

something in common if they are in the same row. All of the

elements in a period have the same number of atomic

orbitals. Every element in the top row (the first period) has

one orbital for its electrons. All of the elements in the

second row (the second period) have two orbitals for their

electrons. It goes down the periodic table like that. At this

time, the maximum number of electron orbitals or electron

shells for any element is seven.

Row = Period

…and Your Groups

Now you know about periods. The periodic table also

has a special name for its columns. When a column

goes from top to bottom, it's called a group. The

elements in a group have the same number of

electrons in their outer orbital. Those outer electrons

are also called valence electrons. They are the ones

involved in chemical bonds with other elements. Columns = Groups

Every element in the first column (group one) has one electron in its outermost

orbit. Every element in the second column (group two) has two electrons in the

outermost orbit. As you keep counting the columns, you'll know how many

electrons are in the outermost orbit. There are some exceptions to the order

when you look at the transition elements, but you get the general idea.

Transition elements start to add electrons to the second-to-last shell.

Families Stick Together

Scientists group these families of elements by their

chemical properties. Each family reacts in a different

way with the outside world. Metals behave differently

than gases, and there are even different types of

metals. Some elements don't react, while others are

very reactive, and some are good conductors of

electricity.

The thing to remember is that a family of elements can be found in several

ways. You need to run tests and study the elements to determine their

properties. Only after that testing can you determine what family an

element belongs in.

Examples of Physical Properties

Density

Boiling Point

Melting Point

Conductivity

Heat Capacity

Examples of Chemical Properties

Valence Electrons

Reactivity

Radioactivity

Hydrogen

1

H

1.008

Who's in the family? Starting at the top we find hydrogen (H). But wait. That

element is NOT in the family. When you learned about families, they were

groups of elements that react in similar ways. Hydrogen is a very special

element of the periodic table and doesn't belong to any family. While hydrogen

sits in Group I, it is NOT an alkali metal.

3

Li

6.941

11

Na

22.99

19

K

39.10

37

Rb

85.47

55

Cs

132.9

87

Fr

(223)

The alkali metals are also metals. That seems obvious

from the name. Often, in chemistry, characteristics are

assigned by the way elements look. You will find that the

alkali group is shiny and light in weight. Their light weight

and physical properties separate them from other metals.

They are malleable (bendable) and sometimes soft

enough to be cut with a dull knife. Alkali metals are not the

type of metals you would use for coins or houses.

Sodium and Water Reaction

Alkali Metals

As with all families, these elements share traits. They are

very reactive. Why? They all have one electron in their

outermost shell. That's one electron away from being

happy (full shells).

Alkaline Earth Metals

4

Be

9.012

12

Mg

24.31

20

Ca

40.08

38

Sr

87.62

56

Ba

137.3

88

Ra

(226)

So we just covered the alkali metals in Group I. You will find

the alkaline earth metals right next door in Group II. This is

the second most reactive family of elements in the periodic

table. Do you know why they are called alkaline? When

these compounds are mixed in solutions, they are likely to

form solutions with a pH greater than 7. Those higher pH

levels means that they are defined as "basic" or "alkaline"

solutions

Transition Metals

21

Sc

44.96

39

Y

88.91

71

Lu

(175)

103

Lr

(275)

22

Ti

47.88

23

V

50.94

24

Cr

52.00

25

Mn

54.94

26

Fe

55.85

27

Co

58.47

28

Ni

58.69

29

Cu

63.55

30

Zn

65.39

40

Zr

91.22

41

Nb

92.91

42

Mo

95.94

43

Tc

(98)

44

Ru

101.1

45

Rh

102.9

46

Pd

106.4

47

Ag

107.9

48

Cd

112.4

72

Hf

178.5

73

Ta

180.9

74

W

183.9

75

Re

186.2

76

Os

190.2

77

Ir

190.2

78

Pt

195.1

79

Au

197.0

80

Hg

200.5

104

Rf

(257)

105

Db

(260)

106

Sg

(263)

107

Bh

(265)

108

Hs

(265)

109

Mt

(266)

110

Ds

(271)

111

Rg

(272)

112

Cn

(277)

Transition Metals Cont.

It all has to do with their shells/orbitals. We like introducing students to the

first eighteen elements, because they are easier to explain. Transition

metals are good examples of advanced shell and orbital ideas. They have a

lot of electrons and distribute them in different ways. You will usually find that

transition metals are shiny, too. Not all of them, but we are sure you've seen

pictures of silver (Ag), gold (Au), and platinum (Pt).

Transition metals can use the two outermost shells/orbitals

to bond with other elements. It's a chemical trait that

allows them to bond with many elements in a variety of

shapes. Why can they do that? As you learn more, you will

discover that most transition elements actually have two

shells that are not happy. Whenever you have a shell that

is not happy, the electrons want to bond with other

elements. Example: Molybdenum (Mo), with 42 electrons.

The configuration is 2-8-18-13-1. The shells with 13 and 1

are not happy.

Basic Metals

13

Al

26.98

31

Ga

69.72

49

In

114.8

81

Tl

204.4

113

Uut

--

50

Sn

118.7

82

Pb

207.2

114

Fl

(296)

83

Bi

209.0

115

Uup

--

116

Lv

(298)

• Shiny 'metallic' appearance

• Solids at room temperature

(except mercury)

• High melting points

• High densities

• Malleable

• Ductile

• Thermal conductors

• Electrical conductors

Metalloids

5

B

10.81

14

Si

28.09

32

Ge

72.59

33

As

74.92

51

Sb

121.8

52

Te

127.6

84

Po

(210)

85

At

(210)

• Possess some characteristics of

metals/some of nonmetals

• Reactivity depends on properties of

other elements in reaction

• Often make good semiconductors

Non-Metals

6

C

12.01

7

N

14.01

8

O

16.00

15

P

30.97

16

S

32.07

34

Se

78.96

• Poor thermal conductors

• Poor electrical conductors

• Brittle solids

• Little or no metallic luster

• Gain electrons easily

Halogens

9

F

19.00

17

Cl

35.45

35

Br

79.90

53

I

126.9

85

At

(210)

When you look at our descriptions of the elements fluorine and

chlorine, you will see that they both have seven electrons in their

outer shell. That seven-electron trait applies to all of the halogens.

They are all just one electron shy of having full shells. Because they

are so close to being happy, they have the trait of combining with

many different elements. They are very reactive. You will often find

them bonding with metals and elements from Group One of the

periodic table. The elements in the column on the left each have one

electron that they like to donate.

Lanthanide Series

57

La

138.9

58

Ce

140.1

59

Pr

140.9

60

Nd

144.2

61

Pm

(147)

62

Sm

150.4

63

Eu

152.0

64

Gd

157.3

65

Tb

158.9

66

Dy

162.5

67

Ho

164.9

68

Er

167.3

69

Tm

168.9

70

Yb

173.0

71

Lu

175.0

When you look at the periodic table, you will see two rows that kind of sit off to the

bottom. They are part of the whole table, but it is easier to print the table when

they are on the bottom. One of those rows is called the lanthanide series. The

lanthanide series can be found naturally on Earth. Some people say lanthanide,

some say rare-earth metals, and some say inner-transition elements. No matter

what you choose, everyone will know what you mean if you say lanthanide

Actinide Series

The actinide series is much different from the lanthanide series. They are all

radioactive and some are not found in nature. Some of the elements with

higher atomic numbers have only been made in labs. There are special

laboratories across the world that specialize in experimenting on elements.

Some of these particle accelerators have pounded atomic particles into

elements with lower atomic numbers. The buildup of additional parts creates

short-lived, high atomic number elements.

89

Ac

(227)

90

Th

232.0

91

Pa

(231)

92

U

(238)

93

Np

(237)

94

Pu

(242)

95

Am

(243)

96

Cm

(247)

97

Bk

(247)

98

Cf

(249)

99

Es

(254)

100

Fm

(253)

101

Md

(256)

102

No

(254)

103

Lr

(257)

Did You Hear?

Two chemist went out to eat at a

restaurant.

The first chemist says, “I’ll have some

H2O”.

The second chemist says, “I think I’ll

have some H2O too”. And he died.