1.Hydrogen
Discovered by:Henry Cavendish
Period:1
Distribution: 1s1
Atomic Mass: 1.008
2.Helium
Discovered by:Pierre Janssen
Period:1
Distribution: 1s2
Atomic Mass: 4.0026022
3.Lithium
Discovered by:Johan August Arfwedson
Period:2
Distribution: [He] 2s1
Atomic Mass: 6.94
4.Beryllium
Discovered by:Louis Nicolas Vauquelin
Period:2
Distribution: [He] 2s2
Atomic Mass: 9.01218315
5.Boron
Discovered by:Joseph Louis Gay-Lussac
Period:2
Distribution: [He] 2s2 2p1
Atomic Mass: 10.81
6.Carbon
Discovered by:Ancient Egypt
Period:2
Distribution: [He] 2s2 2p2
Atomic Mass: 12.011
7.Nitrogen
Discovered by:Daniel Rutherford
Period:2
Distribution: [He] 2s2 2p3
Atomic Mass: 14.007
8.Oxygen
Discovered by:Carl Wilhelm Scheele
Period:2
Distribution: [He] 2s2 2p4
Atomic Mass: 15.999
9.Fluorine
Discovered by:André-Marie Ampère
Period:2
Distribution: [He] 2s2 2p5
Atomic Mass: 18.9984031636
10.Neon
Discovered by:Morris Travers
Period:2
Distribution: [He] 2s2 2p6
Atomic Mass: 20.17976
11.Sodium
Discovered by:Humphry Davy
Period:3
Distribution: [Ne] 3s1
Atomic Mass: 22.989769282
12.Magnesium
Discovered by:Joseph Black
Period:3
Distribution: [Ne] 3s2
Atomic Mass: 24.305
13.Aluminium
Discovered by:
Period:3
Distribution: [Ne] 3s2 3p1
Atomic Mass: 26.98153857
14.Silicon
Discovered by:Jöns Jacob Berzelius
Period:3
Distribution: [Ne] 3s2 3p2
Atomic Mass: 28.085
15.Phosphorus
Discovered by:Hennig Brand
Period:3
Distribution: [Ne] 3s2 3p3
Atomic Mass: 30.9737619985
16.Sulfur
Discovered by:Ancient china
Period:3
Distribution: [Ne] 3s2 3p4
Atomic Mass: 32.06
17.Chlorine
Discovered by:Carl Wilhelm Scheele
Period:3
Distribution: [Ne] 3s2 3p5
Atomic Mass: 35.45
18.Argon
Discovered by:Lord Rayleigh
Period:3
Distribution: [Ne] 3s2 3p6
Atomic Mass: 39.9481
19.Potassium
Discovered by:Humphry Davy
Period:4
Distribution: [Ar] 4s1
Atomic Mass: 39.09831
20.Calcium
Discovered by:Humphry Davy
Period:4
Distribution: [Ar] 4s2
Atomic Mass: 40.0784
21.Scandium
Discovered by:Lars Fredrik Nilson
Period:4
Distribution: [Ar] 3d1 4s2
Atomic Mass: 44.9559085
22.Titanium
Discovered by:William Gregor
Period:4
Distribution: [Ar] 3d2 4s2
Atomic Mass: 47.8671
23.Vanadium
Discovered by:Andrés Manuel del Río
Period:4
Distribution: [Ar] 3d3 4s2
Atomic Mass: 50.94151
24.Chromium
Discovered by:Louis Nicolas Vauquelin
Period:4
Distribution: [Ar] 3d5 4s1
Atomic Mass: 51.99616
25.Manganese
Discovered by:Torbern Olof Bergman
Period:4
Distribution: [Ar] 3d5 4s2
Atomic Mass: 54.9380443
26.Iron
Discovered by:5000 BC
Period:4
Distribution: [Ar] 3d6 4s2
Atomic Mass: 55.8452
27.Cobalt
Discovered by:Georg Brandt
Period:4
Distribution: [Ar] 3d7 4s2
Atomic Mass: 58.9331944
28.Nickel
Discovered by:Axel Fredrik Cronstedt
Period:4
Distribution: [Ar] 3d8 4s2
Atomic Mass: 58.69344
29.Copper
Discovered by:Middle East
Period:4
Distribution: [Ar] 3d10 4s1
Atomic Mass: 63.5463
30.Zinc
Discovered by:India
Period:4
Distribution: [Ar] 3d10 4s2
Atomic Mass: 65.382
31.Gallium
Discovered by:Lecoq de Boisbaudran
Period:4
Distribution: [Ar] 3d10 4s2 4p1
Atomic Mass: 69.7231
32.Germanium
Discovered by:Clemens Winkler
Period:4
Distribution: [Ar] 3d10 4s2 4p2
Atomic Mass: 72.6308
33.Arsenic
Discovered by:Bronze Age
Period:4
Distribution: [Ar] 3d10 4s2 4p3
Atomic Mass: 74.9215956
34.Selenium
Discovered by:Jöns Jakob Berzelius
Period:4
Distribution: [Ar] 3d10 4s2 4p4
Atomic Mass: 78.9718
35.Bromine
Discovered by:Antoine Jérôme Balard
Period:4
Distribution: [Ar] 3d10 4s2 4p5
Atomic Mass: 79.904
36.Krypton
Discovered by:William Ramsay
Period:4
Distribution: [Ar] 3d10 4s2 4p6
Atomic Mass: 83.7982
37.Rubidium
Discovered by:Robert Bunsen
Period:5
Distribution: [Kr] 5s1
Atomic Mass: 85.46783
38.Strontium
Discovered by:William Cruickshank (chemist)
Period:5
Distribution: [Kr] 5s2
Atomic Mass: 87.621
39.Yttrium
Discovered by:Johan Gadolin
Period:5
Distribution: [Kr] 4d1 5s2
Atomic Mass: 88.905842
40.Zirconium
Discovered by:Martin Heinrich Klaproth
Period:5
Distribution: [Kr] 4d2 5s2
Atomic Mass: 91.2242
41.Niobium
Discovered by:Charles Hatchett
Period:5
Distribution: [Kr] 4d4 5s1
Atomic Mass: 92.906372
42.Molybdenum
Discovered by:Carl Wilhelm Scheele
Period:5
Distribution: [Kr] 4d5 5s1
Atomic Mass: 95.951
43.Technetium
Discovered by:Emilio Segrè
Period:5
Distribution: [Kr] 4d5 5s2
Atomic Mass: 98
44.Ruthenium
Discovered by:Karl Ernst Claus
Period:5
Distribution: [Kr] 4d7 5s1
Atomic Mass: 101.072
45.Rhodium
Discovered by:William Hyde Wollaston
Period:5
Distribution: [Kr] 4d8 5s1
Atomic Mass: 102.905502
46.Palladium
Discovered by:William Hyde Wollaston
Period:5
Distribution: [Kr] 4d10
Atomic Mass: 106.421
47.Silver
Discovered by:unknown, before 5000 BC
Period:5
Distribution: [Kr] 4d10 5s1
Atomic Mass: 107.86822
48.Cadmium
Discovered by:Karl Samuel Leberecht Hermann
Period:5
Distribution: [Kr] 4d10 5s2
Atomic Mass: 112.4144
49.Indium
Discovered by:Ferdinand Reich
Period:5
Distribution: [Kr] 4d10 5s2 5p1
Atomic Mass: 114.8181
50.Tin
Discovered by:unknown, before 3500 BC
Period:5
Distribution: [Kr] 4d10 5s2 5p2
Atomic Mass: 118.7107
51.Antimony
Discovered by:unknown, before 3000 BC
Period:5
Distribution: [Kr] 4d10 5s2 5p3
Atomic Mass: 121.7601
52.Tellurium
Discovered by:Franz-Joseph Müller von Reichenstein
Period:5
Distribution: [Kr] 4d10 5s2 5p4
Atomic Mass: 127.603
53.Iodine
Discovered by:Bernard Courtois
Period:5
Distribution: [Kr] 4d10 5s2 5p5
Atomic Mass: 126.904473
54.Xenon
Discovered by:William Ramsay
Period:5
Distribution: [Kr] 4d10 5s2 5p6
Atomic Mass: 131.2936
55.Cesium
Discovered by:Robert Bunsen
Period:6
Distribution: [Xe] 6s1
Atomic Mass: 132.905451966
56.Barium
Discovered by:Carl Wilhelm Scheele
Period:6
Distribution: [Xe] 6s2
Atomic Mass: 137.3277
57.Lanthanum
Discovered by:Carl Gustaf Mosander
Period:6
Distribution: [Xe] 5d16s2
Atomic Mass: 138.905477
58.Cerium
Discovered by:Martin Heinrich Klaproth
Period:6
Distribution: [Xe] 4f1 5d1 6s2
Atomic Mass: 140.1161
59.Praseodymium
Discovered by:Carl Auer von Welsbach
Period:6
Distribution: [Xe] 4f3 6s2
Atomic Mass: 140.907662
60.Neodymium
Discovered by:Carl Auer von Welsbach
Period:6
Distribution: [Xe] 4f4 6s2
Atomic Mass: 144.2423
61.Promethium
Discovered by:Chien Shiung Wu
Period:6
Distribution: [Xe] 4f5 6s2
Atomic Mass: 145
62.Samarium
Discovered by:Lecoq de Boisbaudran
Period:6
Distribution: [Xe] 4f6 6s2
Atomic Mass: 150.362
63.Europium
Discovered by:Eugène-Anatole Demarçay
Period:6
Distribution: [Xe] 4f7 6s2
Atomic Mass: 151.9641
64.Gadolinium
Discovered by:Jean Charles Galissard de Marignac
Period:6
Distribution: [Xe] 4f7 5d1 6s2
Atomic Mass: 157.253
65.Terbium
Discovered by:Carl Gustaf Mosander
Period:6
Distribution: [Xe] 4f9 6s2
Atomic Mass: 158.925352
66.Dysprosium
Discovered by:Lecoq de Boisbaudran
Period:6
Distribution: [Xe] 4f10 6s2
Atomic Mass: 162.5001
67.Holmium
Discovered by:Marc Delafontaine
Period:6
Distribution: [Xe] 4f11 6s2
Atomic Mass: 164.930332
68.Erbium
Discovered by:Carl Gustaf Mosander
Period:6
Distribution: [Xe] 4f12 6s2
Atomic Mass: 167.2593
69.Thulium
Discovered by:Per Teodor Cleve
Period:6
Distribution: [Xe] 4f13 6s2
Atomic Mass: 168.934222
70.Ytterbium
Discovered by:Jean Charles Galissard de Marignac
Period:6
Distribution: [Xe] 4f14 6s2
Atomic Mass: 173.0451
71.Lutetium
Discovered by:Georges Urbain
Period:6
Distribution: [Xe] 4f14 5d1 6s2
Atomic Mass: 174.96681
72.Hafnium
Discovered by:Dirk Coster
Period:6
Distribution: [Xe] 4f14 5d2 6s2
Atomic Mass: 178.492
73.Tantalum
Discovered by:Anders Gustaf Ekeberg
Period:6
Distribution: [Xe] 4f14 5d3 6s2
Atomic Mass: 180.947882
74.Tungsten
Discovered by:Carl Wilhelm Scheele
Period:6
Distribution: [Xe] 4f14 5d4 6s2
Atomic Mass: 183.841
75.Rhenium
Discovered by:Masataka Ogawa
Period:6
Distribution: [Xe] 4f14 5d5 6s2
Atomic Mass: 186.2071
76.Osmium
Discovered by:Smithson Tennant
Period:6
Distribution: [Xe] 4f14 5d6 6s2
Atomic Mass: 190.233
77.Iridium
Discovered by:Smithson Tennant
Period:6
Distribution: [Xe] 4f14 5d7 6s2
Atomic Mass: 192.2173
78.Platinum
Discovered by:Antonio de Ulloa
Period:6
Distribution: [Xe] 4f14 5d9 6s1
Atomic Mass: 195.0849
79.Gold
Discovered by:Middle East
Period:6
Distribution: [Xe] 4f14 5d10 6s1
Atomic Mass: 196.9665695
80.Mercury
Discovered by:unknown, before 2000 BCE
Period:6
Distribution: [Xe] 4f14 5d10 6s2
Atomic Mass: 200.5923
81.Thallium
Discovered by:William Crookes
Period:6
Distribution: [Xe] 4f14 5d10 6s2 6p1
Atomic Mass: 204.38
82.Lead
Discovered by:Middle East
Period:6
Distribution: [Xe] 4f14 5d10 6s2 6p2
Atomic Mass: 207.21
83.Bismuth
Discovered by:Claude François Geoffroy
Period:6
Distribution: [Xe] 4f14 5d10 6s2 6p3
Atomic Mass: 208.980401
84.Polonium
Discovered by:Pierre Curie
Period:6
Distribution: [Xe] 4f14 5d10 6s2 6p4
Atomic Mass: 209
85.Astatine
Discovered by:Dale R. Corson
Period:6
Distribution: [Xe] 4f14 5d10 6s2 6p5
Atomic Mass: 210
86.Radon
Discovered by:Friedrich Ernst Dorn
Period:6
Distribution: [Xe] 4f14 5d10 6s2 6p6
Atomic Mass: 222
87.Francium
Discovered by:Marguerite Perey
Period:7
Distribution: [Rn] 7s1
Atomic Mass: 223
88.Radium
Discovered by:Pierre Curie
Period:7
Distribution: [Rn] 7s2
Atomic Mass: 226
89.Actinium
Discovered by:Friedrich Oskar Giesel
Period:7
Distribution: [Rn] 6d1 7s2
Atomic Mass: 227
90.Thorium
Discovered by:Jöns Jakob Berzelius
Period:7
Distribution: [Rn] 6d2 7s2
Atomic Mass: 232.03774
91.Protactinium
Discovered by:William Crookes
Period:7
Distribution: [Rn] 5f2 6d1 7s2
Atomic Mass: 231.035882
92.Uranium
Discovered by:Martin Heinrich Klaproth
Period:7
Distribution: [Rn] 5f3 6d1 7s2
Atomic Mass: 238.028913
93.Neptunium
Discovered by:Edwin McMillan
Period:7
Distribution: [Rn] 5f4 6d1 7s2
Atomic Mass: 237
94.Plutonium
Discovered by:Glenn T. Seaborg
Period:7
Distribution: [Rn] 5f6 7s2
Atomic Mass: 244
95.Americium
Discovered by:Glenn T. Seaborg
Period:7
Distribution: [Rn] 5f7 7s2
Atomic Mass: 243
96.Curium
Discovered by:Glenn T. Seaborg
Period:7
Distribution: [Rn] 5f7 6d1 7s2
Atomic Mass: 247
97.Berkelium
Discovered by:Lawrence Berkeley National Laboratory
Period:7
Distribution: [Rn] 5f9 7s2
Atomic Mass: 247
98.Californium
Discovered by:Lawrence Berkeley National Laboratory
Period:7
Distribution: [Rn] 5f10 7s2
Atomic Mass: 251
99.Einsteinium
Discovered by:Lawrence Berkeley National Laboratory
Period:7
Distribution: [Rn] 5f11 7s2
Atomic Mass: 252
100.Fermium
Discovered by:Lawrence Berkeley National Laboratory
Period:7
Distribution: [Rn] 5f12 7s2
Atomic Mass: 257
101.Mendelevium
Discovered by:Lawrence Berkeley National Laboratory
Period:7
Distribution: [Rn] 5f13 7s2
Atomic Mass: 258
102.Nobelium
Discovered by:Joint Institute for Nuclear Research
Period:7
Distribution: [Rn] 5f14 7s2
Atomic Mass: 259
103.Lawrencium
Discovered by:Lawrence Berkeley National Laboratory
Period:7
Distribution: [Rn] 5f14 7s2 7p1
Atomic Mass: 266
104.Rutherfordium
Discovered by:Joint Institute for Nuclear Research
Period:7
Distribution: [Rn] 5f14 6d2 7s2
Atomic Mass: 267
105.Dubnium
Discovered by:Joint Institute for Nuclear Research
Period:7
Distribution: *[Rn] 5f14 6d3 7s2
Atomic Mass: 268
106.Seaborgium
Discovered by:Lawrence Berkeley National Laboratory
Period:7
Distribution: *[Rn] 5f14 6d4 7s2
Atomic Mass: 269
107.Bohrium
Discovered by:Gesellschaft für Schwerionenforschung
Period:7
Distribution: *[Rn] 5f14 6d5 7s2
Atomic Mass: 270
108.Hassium
Discovered by:Gesellschaft für Schwerionenforschung
Period:7
Distribution: *[Rn] 5f14 6d6 7s2
Atomic Mass: 269
109.Meitnerium
Discovered by:Gesellschaft für Schwerionenforschung
Period:7
Distribution: *[Rn] 5f14 6d7 7s2
Atomic Mass: 278
110.Darmstadtium
Discovered by:Gesellschaft für Schwerionenforschung
Period:7
Distribution: *[Rn] 5f14 6d9 7s1
Atomic Mass: 281
111.Roentgenium
Discovered by:Gesellschaft für Schwerionenforschung
Period:7
Distribution: *[Rn] 5f14 6d10 7s1
Atomic Mass: 282
112.Copernicium
Discovered by:Gesellschaft für Schwerionenforschung
Period:7
Distribution: *[Rn] 5f14 6d10 7s2
Atomic Mass: 285
113.Nihonium
Discovered by:RIKEN
Period:7
Distribution: *[Rn] 5f14 6d10 7s2 7p1
Atomic Mass: 286
114.Flerovium
Discovered by:Joint Institute for Nuclear Research
Period:7
Distribution: *[Rn] 5f14 6d10 7s2 7p2
Atomic Mass: 289
115.Moscovium
Discovered by:Joint Institute for Nuclear Research
Period:7
Distribution: *[Rn] 5f14 6d10 7s2 7p3
Atomic Mass: 289
116.Livermorium
Discovered by:Joint Institute for Nuclear Research
Period:7
Distribution: *[Rn] 5f14 6d10 7s2 7p4
Atomic Mass: 293
117.Tennessine
Discovered by:Joint Institute for Nuclear Research
Period:7
Distribution: *[Rn] 5f14 6d10 7s2 7p5
Atomic Mass: 294
118.Oganesson
Discovered by:Joint Institute for Nuclear Research
Period:7
Distribution: *[Rn] 5f14 6d10 7s2 7p6
Atomic Mass: 294
1
H
Hydrogen
Hydrogen
Hydrogen is a chemical element with chemical symbol H and atomic number 1. With an atomic weight of 1.00794 u, hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.