The first visible sample of a berkelium compound, made in 1962, weighed only about three billionths of a gram.
Open
1HHydrogen1.008
2HeHelium4.003
3LiLithium6.94
4BeBeryllium9.012
5BBoron10.81
6CCarbon12.011
7NNitrogen14.007
8OOxygen15.999
9FFluorine18.998
10NeNeon20.18
11NaSodium22.99
12MgMagnesium24.305
13AlAluminum26.982
14SiSilicon28.085
15PPhosphorus30.974
16SSulfur32.06
17ClChlorine35.45
18ArArgon39.948
19KPotassium39.098
20CaCalcium40.078
21ScScandium44.956
22TiTitanium47.867
23VVanadium50.942
24CrChromium51.996
25MnManganese54.938
26FeIron55.845
27CoCobalt58.933
28NiNickel58.693
29CuCopper63.546
30ZnZinc65.38
31GaGallium69.723
32GeGermanium72.63
33AsArsenic74.922
34SeSelenium78.971
35BrBromine79.904
36KrKrypton83.798
37RbRubidium85.468
38SrStrontium87.62
39YYttrium88.906
40ZrZirconium91.224
41NbNiobium92.906
42MoMolybdenum95.95
43TcTechnetium98
44RuRuthenium101.07
45RhRhodium102.91
46PdPalladium106.42
47AgSilver107.87
48CdCadmium112.41
49InIndium114.82
50SnTin118.71
51SbAntimony121.76
52TeTellurium127.6
53IIodine126.9
54XeXenon131.29
55CsCesium132.91
56BaBarium137.33
57LaLanthanum138.91
58CeCerium140.12
59PrPraseodymium140.91
60NdNeodymium144.24
61PmPromethium145
62SmSamarium150.36
63EuEuropium151.96
64GdGadolinium157.25
65TbTerbium158.93
66DyDysprosium162.5
67HoHolmium164.93
68ErErbium167.26
69TmThulium168.93
70YbYtterbium173.05
71LuLutetium174.97
72HfHafnium178.49
73TaTantalum180.95
74WTungsten183.84
75ReRhenium186.21
76OsOsmium190.23
77IrIridium192.22
78PtPlatinum195.08
79AuGold196.97
80HgMercury200.59
81TlThallium204.38
82PbLead207.2
83BiBismuth208.98
84PoPolonium209
85AtAstatine210
86RnRadon222
87FrFrancium223
88RaRadium226
89AcActinium227
90ThThorium232.04
91PaProtactinium231.04
92UUranium238.03
93NpNeptunium237
94PuPlutonium244
95AmAmericium243
96CmCurium247
97BkBerkelium247
98CfCalifornium251
99EsEinsteinium252
100FmFermium257
101MdMendelevium258
102NoNobelium259
103LrLawrencium266
104RfRutherfordium267
105DbDubnium268
106SgSeaborgium269
107BhBohrium270
108HsHassium277
109MtMeitnerium278
110DsDarmstadtium281
111RgRoentgenium282
112CnCopernicium285
113NhNihonium286
114FlFlerovium289
115McMoscovium290
116LvLivermorium293
117TsTennessine294
118OgOganesson294
57–71La–LuLanthanides
89–103Ac–LrActinides
Periodic Table of Elements
Hover over an element to see its data. Click to open its full page.
Alkali metal
Alkaline earth metal
Transition metal
Post-transition metal
Metalloid
Reactive nonmetal
Halogen
Noble gas
Lanthanide
Actinide
Unknown properties
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New cards every dayWhat is the symbol for Cobalt?
Answer
Co · CobaltAnion
A negatively charged ion, formed when an atom or group of atoms gains one or more electrons.
OpenIron(II,III) oxide Fe3O4
The molar mass of iron(II,III) oxide (Fe3O4) is 231.531 g/mol.
OpenPercent yield calculator
Compare the product you actually made with the most you could have made. Solve for the percent yield, the actual yield or the theoretical yield.
OpenWhat are isotopes?
Isotopes are atoms of the same element that have different numbers of neutrons. They have the same number of protons, so they are the same element and react in almost exactly the same way, but their masses are different. Carbon-12 and carbon-14 are two isotopes of carbon.
OpenWhat is the periodic table?
The periodic table arranges all 118 known chemical elements in order of atomic number – the number of protons in the nucleus of each atom. Rows are called periods and columns are called groups. Elements in the same group have the same number of outer electrons, so they behave in similar ways: the alkali metals in group 1 all react with water, while the noble gases in group 18 hardly react at all.
Dmitri Mendeleev published the first widely accepted version in 1869. He left gaps for elements nobody had found yet and predicted their properties; gallium, scandium and germanium were discovered over the next 17 years and matched his predictions. Today the table is complete up to element 118, oganesson.
How to read the periodic table
Each box shows one element: its atomic number at the top, its chemical symbol in the middle, then its name and its atomic mass in grams per mole.
The colors sort the elements into families such as the alkali metals, transition metals, halogens and noble gases. Metals fill the left and center of the table, nonmetals sit at the upper right, and the metalloids form a staircase between them.
The two rows at the bottom are the lanthanides and actinides. They belong in periods 6 and 7 but are shown separately so the table does not become too wide.
Hover over or tap any element to see its electron configuration, electronegativity, melting and boiling points, density and discovery year, then open its page for the full story.