Periodic table

Simple Periodic Table Chart-en.svg

The periodic table, also known as the periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties. The structure of the table shows periodic trends. The seven rows of the table, called periods, generally have metals on the left and non-metals on the right. The columns, called groups, contain elements with similar chemical behaviours. Six groups have accepted names as well as assigned numbers: for example, group 17 elements are the halogens; and group 18 are the noble gases. Also displayed are four simple rectangular areas or blocks associated with the filling of different atomic orbitals.

The elements from atomic numbers 1 (hydrogen) through 118 (oganesson) have been discovered or synthesized, completing seven full rows of the periodic table.[1][2] The first 94 elements all occur naturally, though some are found only in trace amounts and a few were discovered in nature only after having first been synthesized.[n 1] Elements 95 to 118 have only been synthesized in laboratories or nuclear reactors.[3] The synthesis of elements having higher atomic numbers is currently being pursued: these elements would begin an eighth row, and theoretical work has been done to suggest possible candidates for this extension. Numerous synthetic radionuclides of naturally occurring elements have also been produced in laboratories.

The organization of the periodic table can be used to derive relationships between the various element properties, and also to predict chemical properties and behaviours of undiscovered or newly synthesized elements. Russian chemist Dmitri Mendeleev published the first recognizable periodic table in 1869, developed mainly to illustrate periodic trends of the then-known elements. He also predicted some properties of unidentified elements that were expected to fill gaps within the table. Most of his forecasts proved to be correct. Mendeleev's idea has been slowly expanded and refined with the discovery or synthesis of further new elements and the development of new theoretical models to explain chemical behaviour. The modern periodic table now provides a useful framework for analyzing chemical reactions, and continues to be widely used in chemistry, nuclear physics and other sciences.

Overview

Group 1 2 3   4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Alkali metals Alkaline earth metals Pnicto­gens Chal­co­gens Halo­gens Noble gases
Period

1

1.008 4.0026
2 6.94 9.0122 10.81 12.011 14.007 15.999 18.998 20.180
3 22.990 24.305 26.982 28.085 30.974 32.06 35.45 39.95
4 39.098 40.078 44.956 47.867 50.942 51.996 54.938 55.845 58.933 58.693 63.546 65.38 69.723 72.630 74.922 78.971 79.904 83.798
5 85.468 87.62 88.906 91.224 92.906 95.95 ​[97] 101.07 102.91 106.42 107.87 112.41 114.82 118.71 121.76 127.60 126.90 131.29
6 132.91 137.33 138.91 1 asterisk 178.49 180.95 183.84 186.21 190.23 192.22 195.08 196.97 200.59 204.38 207.2 208.98 ​[209] ​[210] ​[222]
7 ​[223] ​[226] ​[227] 1 asterisk ​[267] ​[268] ​[269] ​[270] ​[269] ​[278] ​[281] ​[282] ​[285] ​[286] ​[289] ​[290] ​[293] ​[294] ​[294]
1 asterisk 140.12 140.91 144.24 ​[145] 150.36 151.96 157.25 158.93 162.50 164.93 167.26 168.93 173.05 174.97  
1 asterisk 232.04 231.04 238.03 ​[237] ​[244] ​[243] ​[247] ​[247] ​[251] ​[252] ​[257] ​[258] ​[259] ​[266]
Group → 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Alkali metal Alkaline earth metal Boron group Carbon group Pnictogen Chalcogen Halogen Noble gas
CAS: IA IIA IIIB IVB VB VIB VIIB VIIIB IB IIB IIIA IVA VA VIA VIIA VIIIA
old IUPAC: IA IIA IIIA IVA VA VIA VIIA VIII IB IIB IIIB IVB VB VIB VIIB 0
Period ↓Period ↓ Hydrogen
1
 
  • 1.008
  • [1.00781.0082]
element name
atomic number
chemical symbol

Helium
2
 
  • 4.0026
  • 4.002602(2)
2 Lithium
3
 
  • 6.94
  • [6.9386.997]
Beryllium
4
 
  • 9.0122
  • 9.0121831(5)
Boron
5
 
  • 10.81
  • [10.80610.821]
Carbon
6
 
  • 12.011
  • [12.00912.012]
Nitrogen
7
 
  • 14.007
  • [14.00614.008]
Oxygen
8
 
  • 15.999
  • [15.99916.000]
Fluorine
9
 
  • 18.998
  • 18.998403163(6)
Neon
10
 
  • 20.180
  • 20.1797(6)
3 Sodium
11
 
  • 22.990
  • 22.98976928(2)
Magnesium
12
 
  • 24.305
  • [24.30424.307]
Aluminium
13
 
  • 26.982
  • 26.9815384(3)
Silicon
14
 
  • 28.085
  • [28.08428.086]
Phosphorus
15
 
  • 30.974
  • 30.973761998(5)
Sulfur
16
 
  • 32.06
  • [32.05932.076]
Chlorine
17
 
  • 35.45
  • [35.44635.457]
Argon
18
 
  • 39.95
  • [39.79239.963]
4 Potassium
19
 
  • 39.098
  • 39.0983(1)
Calcium
20
 
  • 40.078(4)
  • 40.078(4)
Scandium
21
 
  • 44.956
  • 44.955908(5)
Titanium
22
 
  • 47.867
  • 47.867(1)
Vanadium
23
 
  • 50.942
  • 50.9415(1)
Chromium
24
 
  • 51.996
  • 51.9961(6)
Manganese
25
 
  • 54.938
  • 54.938043(2)
Iron
26
 
  • 55.845(2)
  • 55.845(2)
Cobalt
27
 
  • 58.933
  • 58.933194(3)
Nickel
28
 
  • 58.693
  • 58.6934(4)
Copper
29
 
  • 63.546(3)
  • 63.546(3)
Zinc
30
 
  • 65.38(2)
  • 65.38(2)
Gallium
31
 
  • 69.723
  • 69.723(1)
Germanium
32
 
  • 72.630(8)
  • 72.630(8)
Arsenic
33
 
  • 74.922
  • 74.921595(6)
Selenium
34
 
  • 78.971(8)
  • 78.971(8)
Bromine
35
 
  • 79.904
  • [79.90179.907]
Krypton
36
 
  • 83.798(2)
  • 83.798(2)
5 Rubidium
37
 
  • 85.468
  • 85.4678(3)
Strontium
38
 
  • 87.62
  • 87.62(1)
Yttrium
39
 
  • 88.906
  • 88.90584(1)
Zirconium
40
 
  • 91.224(2)
  • 91.224(2)
Niobium
41
 
  • 92.906
  • 92.90637(1)
Molybdenum
42
 
  • 95.95
  • 95.95(1)
Technetium
43
 
[97]
Ruthenium
44
 
  • 101.07(2)
  • 101.07(2)
Rhodium
45
 
  • 102.91
  • 102.90549(2)
Palladium
46
 
  • 106.42
  • 106.42(1)
Silver
47
 
  • 107.87
  • 107.8682(2)
Cadmium
48
 
  • 112.41
  • 112.414(4)
Indium
49
 
  • 114.82
  • 114.818(1)
Tin
50
 
  • 118.71
  • 118.710(7)
Antimony
51
 
  • 121.76
  • 121.760(1)
Tellurium
52
 
  • 127.60(3)
  • 127.60(3)
Iodine
53
 
  • 126.90
  • 126.90447(3)
Xenon
54
 
  • 131.29
  • 131.293(6)
6 Caesium
55
 
  • 132.91
  • 132.90545196(6)
Barium
56
 
  • 137.33
  • 137.327(7)
Lanthanum
57
 
  • 138.91
  • 138.90547(7)

58–71
1 asterisk
Hafnium
72
 
  • 178.49(2)
  • 178.49(2)
Tantalum
73
 
  • 180.95
  • 180.94788(2)
Tungsten
74
 
  • 183.84
  • 183.84(1)
Rhenium
75
 
  • 186.21
  • 186.207(1)
Osmium
76
 
  • 190.23(3)
  • 190.23(3)
Iridium
77
 
  • 192.22
  • 192.217(2)
Platinum
78
 
  • 195.08
  • 195.084(9)
Gold
79
 
  • 196.97
  • 196.966570(4)
Mercury
80
 
  • 200.59
  • 200.592(3)
Thallium
81
 
  • 204.38
  • [204.38204.39]
Lead
82
 
  • 207.2
  • 207.2(1)
Bismuth
83
 
  • 208.98
  • 208.98040(1)
Polonium
84
 
[209]
Astatine
85
 
[210]
Radon
86
 
[222]
7 Francium
87
 
[223]
Radium
88
 
[226]
Actinium
89
 
[227]

90–103
1 asterisk
Rutherfordium
104
 
[267]
Dubnium
105
 
[268]
Seaborgium
106
 
[269]
Bohrium
107
 
[270]
Hassium
108
 
[269]
Meitnerium
109
 
[278]
Darmstadtium
110
 
[281]
Roentgenium
111
 
[282]
Copernicium
112
 
[285]
Nihonium
113
 
[286]
Flerovium
114
 
[289]
Moscovium
115
 
[290]
Livermorium
116
 
[293]
Tennessine
117
 
[294]
Oganesson
118
 
[294]

1 asterisk Cerium
58
 
  • 140.12
  • 140.116(1)
Praseodymium
59
 
  • 140.91
  • 140.90766(1)
Neodymium
60
 
  • 144.24
  • 144.242(3)
Promethium
61
 
[145]
Samarium
62
 
  • 150.36(2)
  • 150.36(2)
Europium
63
 
  • 151.96
  • 151.964(1)
Gadolinium
64
 
  • 157.25(3)
  • 157.25(3)
Terbium
65
 
  • 158.93
  • 158.925354(8)
Dysprosium
66
 
  • 162.50
  • 162.500(1)
Holmium
67
 
  • 164.93
  • 164.930328(7)
Erbium
68
 
  • 167.26
  • 167.259(3)
Thulium
69
 
  • 168.93
  • 168.934218(6)
Ytterbium
70
 
  • 173.05
  • 173.045(10)
Lutetium
71
 
  • 174.97
  • 174.9668(1)
1 asterisk Thorium
90
 
  • 232.04
  • 232.0377(4)
Protactinium
91
 
  • 231.04
  • 231.03588(1)
Uranium
92
 
  • 238.03
  • 238.02891(3)
Neptunium
93
 
[237]
Plutonium
94
 
[244]
Americium
95
 
[243]
Curium
96
 
[247]
Berkelium
97
 
[247]
Californium
98
 
[251]
Einsteinium
99
 
[252]
Fermium
100
 
[257]
Mendelevium
101
 
[258]
Nobelium
102
 
[259]
Lawrencium
103
 
[266]

Each chemical element has a unique atomic number (Z) representing the number of protons in its nucleus.[n 2] Most elements have differing numbers of neutrons among different atoms, with these variants being referred to as isotopes. For example, carbon has three naturally occurring isotopes: all of its atoms have six protons and most have six neutrons as well, but about one per cent have seven neutrons, and a very small fraction have eight neutrons. Isotopes are never separated in the periodic table; they are always grouped together under a single element. Elements with no stable isotopes have the atomic masses of their most stable isotopes, where such masses are shown, listed in parentheses.[9]

In the standard periodic table, the elements are listed in order of increasing atomic number Z (the number of protons in the nucleus of an atom). A new row (period) is started when a new electron shell has its first electron. Columns (groups) are determined by the electron configuration of the atom; elements with the same number of electrons in a particular subshell fall into the same columns (e.g. oxygen and selenium are in the same column because they both have four electrons in the outermost p-subshell). Elements with similar chemical properties generally fall into the same group in the periodic table, although in the f-block, and to some respect in the d-block, the elements in the same period tend to have similar properties, as well. Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it.[10]

Since 2016, the periodic table has 118 confirmed elements, from element 1 (hydrogen) to 118 (oganesson). Elements 113, 115, 117 and 118, the most recent discoveries, were officially confirmed by the International Union of Pure and Applied Chemistry (IUPAC) in December 2015. Their proposed names, nihonium (Nh), moscovium (Mc), tennessine (Ts) and oganesson (Og) respectively, were announced by the IUPAC in June 2016 and made official in November 2016.[11][12][13][14]

The first 94 elements occur naturally; the remaining 24, americium to oganesson (95–118), occur only when synthesized in laboratories. Of the 94 naturally occurring elements, 83 are primordial and 11 occur only in decay chains of primordial elements.[3] No element heavier than einsteinium (element 99) has ever been observed in macroscopic quantities in its pure form, nor has astatine (element 85); francium (element 87) has been only photographed in the form of light emitted from microscopic quantities (300,000 atoms).[15]

Other Languages
Afrikaans: Periodieke tabel
Alemannisch: Periodensystem
العربية: جدول دوري
asturianu: Tabla periódica
Bân-lâm-gú: Chiu-kî-piáu
беларуская (тарашкевіца)‎: Пэрыядычная сыстэма хімічных элемэнтаў
Boarisch: Periodnsystem
Cymraeg: Tabl cyfnodol
ދިވެހިބަސް: ޕީރިއަޑިކް ތާވަލު
Esperanto: Perioda tabelo
Fiji Hindi: Periodic table
Gàidhlig: Clàr pillteach
Gĩkũyũ: Metha Njokereri
ગુજરાતી: આવર્ત કોષ્ટક
客家語/Hak-kâ-ngî: Ngièn-su chû-khì-péu
한국어: 주기율표
বিষ্ণুপ্রিয়া মণিপুরী: পর্যায় সারণী
Bahasa Indonesia: Tabel periodik
íslenska: Lotukerfið
Kiswahili: Mfumo radidia
lumbaart: Taula periodica
Bahasa Melayu: Jadual berkala
Minangkabau: Tabel periodik
Mìng-dĕ̤ng-ngṳ̄: Nguòng-só ciŭ-gĭ-biēu
Nederlands: Periodiek systeem
नेपाल भाषा: तत्त्वमां
日本語: 周期表
norsk nynorsk: Periodesystemet
oʻzbekcha/ўзбекча: Kimyoviy elementlar davriy sistemasi
Papiamentu: Mesa periodiko
Piemontèis: Tàula periòdica
Plattdüütsch: Periodensystem
português: Tabela periódica
Simple English: Periodic table
Sranantongo: Periodiki sistemi
српски / srpski: Периодни систем
srpskohrvatski / српскохрватски: Periodni sistem elemenata
Taqbaylit: Ayiren imezzi
tarandíne: Tavele Periodiche
Türkçe: Periyodik tablo
Tiếng Việt: Bảng tuần hoàn
West-Vlams: Periodiek système