Periodic table

The periodic table is a table that puts all known chemical elements in a specific order. Elements that have similar characteristics are often put near each other. In the table, the elements are placed in the order of their atomic numbers starting with the lowest number of one, hydrogen. The atomic number of an element is the same as the number of protons in that particular nucleus of an atom. In the table the elements are arranged into periods and group. A row of elements across the table is called a period. Each period has a number; from 1 to 8. Period 1 has only 2 elements in it: hydrogen and helium. Period 2 and Period 3 both have 8 elements. Other periods are longer. Elements in a period have consecutive atomic numbers.

A standard periodic table

A column 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, according to the number of valency electrons, 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.

There are two systems of group numbers; one using Arabic numerals (1,2,3) and the other using Roman numerals (I, II, III). The Roman numeral names were used in most of the 20th century. In 1990 the International Union of Pure and Applied Chemistry (IUPAC) decided to use the new system with Arabic numerals, to replace the two old group systems that used Roman numerals.

The periodic table has been used by chemists to observe patterns and relationships between elements. There are 3 main groups in the Periodic Table; metals, metalloids, and nonmetals. For example, elements to the bottom and far left of the table are the most metallic, and elements on the top right are the least metallic. (e.g. caesium is much more metallic than helium). There are also many other patterns and relationships.

The periodic table was invented by the Russian chemist Dmitry Ivanovich Mendeleyev (1834–1907). In his honor, element 101 was named after him, mendelevium.

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 Hydrogen

2 He Helium

2

3 Li Lithium

4 Be Beryllium

5 B Boron

6 C Carbon

7 N Nitrogen

8 O Oxygen

9 F Fluorine

10 Ne Neon

3

11 Na Sodium

12 Mg Magnesium

13 Al Aluminium

14 Si Silicon

15 P Phosphorus

16 S Sulfur

17 Cl Chlorine

18 Ar Argon

4

19 K Potassium

20 Ca Calcium

21 Sc Scandium

22 Ti Titanium

23 V Vanadium

24 Cr Chromium

25 Mn Manganese

26 Fe Iron

27 Co Cobalt

28 Ni Nickel

29 Cu Copper

30 Zn Zinc

31 Ga Gallium

32 Ge Germanium

33 As Arsenic

34 Se Selenium

35 Br Bromine

36 Kr Krypton

5

37 Rb Rubidium

38 Sr Strontium

39 Y Yttrium

40 Zr Zirconium

41 Nb Niobium

42 Mo Molybdenum

43 Tc Technetium

44 Ru Ruthenium

45 Rh Rhodium

46 Pd Palladium

47 Ag Silver

48 Cd Cadmium

49 In Indium

50 Sn Tin

51 Sb Antimony

52 Te Tellurium

53 I Iodine

54 Xe Xenon

6

55 Cs Cesium

56 Ba Barium

* Lanthanides

72 Hf Halfnium

73 Ta Tantalum

74 W Tungsten

75 Re Rhenium

76 Os Osmium

77 Ir Iridium

78 Pt Platinum

79 Au Gold

80 Hg Mercury

81 Tl Thallium

82 Pb Lead

83 Bi Bismuth

84 Po Polonium

85 At Astatine

86 Rn Radon

7

87  Fr Francium

88 Ra Radium

** Actinides

104 Rf Rutherfordium

105 Db Dubnium

106 Sg Seaborgium

107 Bh Bohrium

108 Hs Hassium

109 Mt Meitnerium

110 Ds Darmstadtium

111 Rg Roentgenium

112 Cn Copernicium

113 Nh Nihonium

114 Fl Flerovium

115 Mc Moscovium

116 Lv Livermorium

117 Ts Tennesine

118 Og Oganesson

8

119  Uue Ununennium

120 Ubn Unbinilium

You

* Lanthanide Series

57 La Lanthanum

58 Ce Cerium

59 Pr Praseodymium

60 Nd Neodymium

61 Pm Promethium

62 Sm Samarium

63 Eu Europium

64 Gd Gadolinium

65 Tb Terbium

66 Dy Dysprosium

67 Ho Holmium

68 Er Erbium

69 Tm Thulium

70 Yb Ytterbium

71 Lu Lutetium

** Actinide Series

89 Ac Actinium

90 Th Thorium

91 Pa Protactinium

92 U Uranium

93 Np Neptunium

94 Pu Plutonium

95 Am Americium

96 Cm Curium

97 Bk Berkelium

98 Cf Californium

99 Es Einsteinium

100 Fm Fermium

101 Md Mendeleevium

102 No Nobelium

103 Lr Lawrencium

Chemical Series of the Periodic Table

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

State at standard temperature and pressure. The color of the number (atomic number) above the element symbol shows the state of the element at normal conditions.

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

Radioactivity

• Those with solid 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.

Other arrangements of the Periodic Table

The version of the periodic table shown above is the one most used. Other widespread versions are shown below:

• 
  Theodor Benfey arranged the elements in a spiral, around hydrogen. The atomic weight determines the position of the element.
• 
  Dmitry Ivanovich Mendeleyev used a flower arrangement; Actinides, Lanthanides are shown as loops beside the main group.
• 
  Timothy Stove arranged the elements by quantum number.
• 
  Betterman arranged the elements by their isoelectric properties, which can be converted to a polynomial form.
• 
  Triangular version, by Zmaczynski and Bayley
• 
  Arranged in a pyramid.

Other versions

• The standard table provides the basics. It is shown above
• A vertical table for improved readability 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: includes name, symbol, atomic number, atomic mass, group, and period; sortable by any of those
• List of elements by symbol
• List of elements by boiling point
• List of elements by melting point
• List of elements by density

Related pages

• Periodic table group
• Periodic table period
• Extended periodic table

Other websites

• Periodic Table of the Elements – displays basic properties
• WebElements Periodic table

https://www.britannica.com/story/when-was-the-periodic-table-invented

https://origins.osu.edu/milestones/mendeleev-periodic-table-UN-chemistry-radioactivity-noble-gases