Periodic table

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The periodic table of the chemical elements is a list of known atoms (chemical elements). In the table the elements are placed in the order of their atomic numbers starting with the lowest number. The atomic number of an element is the same as the number of electrons or protons in the atom.

In the periodic table the elements are arranged into periods and groups.

A row of elements across the table is called a period. Each period has a number: from 1 to 7. Period 1 has only 2 elements in it: hydrogen and helium. Period 2 and Period 3 both have 8 elements. Other periods are longer.

A row of elements down the table is called a group. There are 18 groups in the standard periodic table. Each group has a number: from 1 to 18. Elements in a group have electrons arranged in similar ways, which gives them similar chemical properties (they behave in similar ways). For example, group 18 is known as the noble gases because they are all gases and they do not combine with other atoms.

The periodic table can be used by chemists to observe patterns, and relationships between the elements. For example, elements to the top and far left of the table are the most metallic, and elements on the bottom right are the least metallic. (e.g lithium is much more metallic than xenon). There are also many other patterns and relationships.

There are three systems of group numbers; one using Arabic numerals (1,2,3) and the other two using Roman numerals (I, II, III). The Roman numeral names were used at first and are the traditional names; the Arabic numeral names are newer names that the International Union of Pure and Applied Chemistry (IUPAC) decided to use as well. The IUPAC names were meant to replace the older Roman numeral systems as they used the same names to mean different things, which was confusing.

The Periodic Table was invented and arranged by the Russian chemist Dimitri Mendeleev (1834-1907). He got the idea from his favourite card game, Patience.^{[needs proving]}

Contents 1 Standard periodic table 2 Other methods for displaying the chemical elements 3 See also 4 Other websites

[change] Standard periodic table

Group →

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

Period ↓

1

1 H

2 He

2

3 Li

4 Be

5 B

6 C

7 N

8 O

9 F

10 Ne

3

11 Na

12 Mg

13 Al

14 Si

15 P

16 S

17 Cl

18 Ar

4

19 K

20 Ca

21 Sc

22 Ti

23 V

24 Cr

25 Mn

26 Fe

27 Co

28 Ni

29 Cu

30 Zn

31 Ga

32 Ge

33 As

34 Se

35 Br

36 Kr

5

37 Rb

38 Sr

39 Y

40 Zr

41 Nb

42 Mo

43 Tc

44 Ru

45 Rh

46 Pd

47 Ag

48 Cd

49 In

50 Sn

51 Sb

52 Te

53 I

54 Xe

6

55 Cs

56 Ba

*

72 Hf

73 Ta

74 W

75 Re

76 Os

77 Ir

78 Pt

79 Au

80 Hg

81 Tl

82 Pb

83 Bi

84 Po

85 At

86 Rn

7

87  Fr

88 Ra

**

104 Rf

105 Db

106 Sg

107 Bh

108 Hs

109 Mt

110 Ds

111 Rg

112 Uub

113 Uut

114 Uuq

115 Uup

116 Uuh

117 Uus

118 Uuo

* Lanthanides

57 La

58 Ce

59 Pr

60 Nd

61 Pm

62 Sm

63 Eu

64 Gd

65 Tb

66 Dy

67 Ho

68 Er

69 Tm

70 Yb

71 Lu

** Actinides

89 Ac

90 Th

91 Pa

92 U

93 Np

94 Pu

95 Am

96 Cm

97 Bk

98 Cf

99 Es

100 Fm

101 Md

102 No

103 Lr

Chemical Series of the Periodic Table

• Alkali metals
• Alkaline earths
• Lanthanides
• Actinides
• Transition metals
• Poor metals
• Metalloids
• Nonmetals
• Halogens
• Noble gases

State at standard temperature and pressure

• those in blue are gases
• those in green are liquids
• those in black are solid

Radioactivity

• those with soild borders have stable isotopes (Primordial elements)
• those with dashed borders have only radioactive naturally occurring isotopes
• those with dotted borders do not occur naturally (Synthetic Elements)
• those without borders are too radioactive to have been discovered yet

[change] Other methods for displaying the chemical elements

• The standard table provides the basics. It is shown above.
• A vertical table for improved readablity in web browsers
• The big table provides the basics plus full element names.
• The huge table provides the basics plus full element names and atomic masses.
• Electron Configurations
• Metals and Non Metals
• List of elements by name
• List of elements by symbol
• List of elements by atomic number
• List of elements by boiling point
• List of elements by melting point
• List of elements by density
• List of elements by atomic mass

[change] See also

• Periodic table group
• Periodic table period
• Chemical series
• Periodic table block
• Isotope table (complete)
• Isotope table (divided)

[change] Other websites

• Periodic Table of the Elements - displays basic properties
• The Pictorial Periodic Table
• WebElements Periodic table
• New Periodic Table of the Chemical Elements - triangular table