IUPAC · 118 elementsPeriods 1–7

Calibrating
the table.

000
Vt Vitrine
00 — The cell
He · C · Fe · Au Index

IUPAC periodic system / ordered by atomic number

ZAr

Vt

Vitrine
How to read a cell · not an element

Atomic number at left. Standard atomic weight at right. Symbol at centre. Every element on the table is filed that way.

Advance period ↓
01 / Periodic law

Mendeleev ordered by mass. Moseley found the number. The table follows Z.

Chemical properties are a periodic function of atomic number — the count of protons in the nucleus.

02 / Group key
Group 11 · d-block

Coinage

Copper, silver, gold. Filled d-orbitals and high conductivity. Gold is the most noble of the three: it does not oxidise in air.

Group 18 · noble gases

Noble

Closed valence shells. Helium holds the highest first ionisation energy of any element, and the lowest boiling point.

Group 14 · p-block

Tetrels

Four valence electrons. Carbon catenates uniquely — diamond, graphite, graphene — and is the backbone of living chemistry.

Group 8 · d-block

Iron group

Iron, ruthenium, osmium. Iron is ferromagnetic below 1043 K and accounts for most of the mass of Earth’s core.

He · C · Fe · Au / periods 1, 2, 4, 6Translate →
Z = 79 · Period 6 · Group 11

Gold

Au · 196.97

Transition metal. Configuration [Xe] 4f¹⁴ 5d¹⁰ 6s¹. One stable isotope, ¹⁹⁷Au. Density 19.32 g·cm⁻³; it does not rust. Relativistic contraction of the 6s orbital is why the metal looks yellow.

Noble metald-blockMonoisotopic
196.97 standard atomic weight
19.32 g·cm⁻³ at 20 °C
SampleAu · 79 · native metal
GoldGroup 11 · Coinage
Does not
oxidise.
19.32 g·cm⁻³
Z = 2 · Period 1 · Group 18

Helium

He · 4.0026

Noble gas. Configuration 1s². Seen first in the solar spectrum in 1868; isolated on Earth in 1895. First ionisation energy 24.59 eV — the highest of any element. Boils at 4.22 K. Monatomic, inert, will not burn.

Noble gas1s²Inert
4.0026 standard atomic weight
24.59 eV first ionisation
SampleHe · 2 · noble gas
HeliumGroup 18 · Closed shell
Lowest boiling pointBoils at
4.22 kelvin.
Z = 6 · Period 2 · Group 14

Carbon

C · 12.011

Nonmetal. Four valence electrons. Forms diamond (sp³), graphite (sp²), graphene and fullerenes. The standard atomic weight is an interval because ¹²C/¹³C varies in nature. The chemistry of carbon is the chemistry of life.

TetrelAllotropesTetravalent
12.011 standard atomic weight
4 valence electrons
SampleC · 6 · p-block
CarbonGroup 14
sp³ · sp² · spThe lattice
of living matter.
Z = 26 · Period 4 · Group 8

Iron

Fe · 55.845

Transition metal. Configuration [Ar] 3d⁶ 4s². Ferromagnetic below the Curie point of 1043 K. α-iron is body-centred cubic at room temperature. ⁵⁶Fe sits near the peak of nuclear binding energy; Earth’s core is predominantly iron.

d-blockFerromagneticBCC
55.845 standard atomic weight
1043 K Curie point
SampleFe · 26 · α-iron
IronGroup 8 · BCC
Ferromagnetic
below 1043 K.
04 / How the table was built

Count the protons.
Then watch the chemistry recur.

  1. 01

    Observe

    Spectra, combining weights, density, melting point. Record only what another laboratory can reproduce.

  2. 02

    Order

    By atomic number Z — the proton count. Atomic mass nearly tracks Z, but tellurium is heavier than iodine; the table follows Z, not mass.

  3. 03

    Group

    Same valence electron count, similar chemistry. That is why the columns are numbered 1–18, and why helium sits with the noble gases despite a 1s² configuration.

  4. 04

    Predict

    Mendeleev’s gaps were later filled — gallium, germanium, scandium. The named table now runs to 118. Elements 119 and beyond remain unconfirmed.

05 / IUPAC periodic table

The periodic table of the elements.

Eighteen groups, seven periods. Ordered by atomic number. Helium, carbon, iron and gold are isolated in the hall above; every other cell is a real, named element.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
1
1HHydrogen
2HeHelium
2
3LiLithium
4BeBeryllium
5BBoron
6CCarbon
7NNitrogen
8OOxygen
9FFluorine
10NeNeon
3
11NaSodium
12MgMagnesium
13AlAluminium
14SiSilicon
15PPhosphorus
16SSulfur
17ClChlorine
18ArArgon
4
19KPotassium
20CaCalcium
21ScScandium
22TiTitanium
23VVanadium
24CrChromium
25MnManganese
26FeIron
27CoCobalt
28NiNickel
29CuCopper
30ZnZinc
31GaGallium
32GeGermanium
33AsArsenic
34SeSelenium
35BrBromine
36KrKrypton
5
37RbRubidium
38SrStrontium
39YYttrium
40ZrZirconium
41NbNiobium
42MoMolybdenum
43TcTechnetium
44RuRuthenium
45RhRhodium
46PdPalladium
47AgSilver
48CdCadmium
49InIndium
50SnTin
51SbAntimony
52TeTellurium
53IIodine
54XeXenon
6
55CsCaesium
56BaBarium
57LaLanthanum
72HfHafnium
73TaTantalum
74WTungsten
75ReRhenium
76OsOsmium
77IrIridium
78PtPlatinum
79AuGold
80HgMercury
81TlThallium
82PbLead
83BiBismuth
84PoPolonium
85AtAstatine
86RnRadon
7
87FrFrancium
88RaRadium
89AcActinium
104RfRutherfordium
105DbDubnium
106SgSeaborgium
107BhBohrium
108HsHassium
109MtMeitnerium
110DsDarmstadtium
111RgRoentgenium
112CnCopernicium
113NhNihonium
114FlFlerovium
115McMoscovium
116LvLivermorium
117TsTennessine
118OgOganesson
Ln
58CeCerium
59PrPraseodymium
60NdNeodymium
61PmPromethium
62SmSamarium
63EuEuropium
64GdGadolinium
65TbTerbium
66DyDysprosium
67HoHolmium
68ErErbium
69TmThulium
70YbYtterbium
71LuLutetium
An
90ThThorium
91PaProtactinium
92UUranium
93NpNeptunium
94PuPlutonium
95AmAmericium
96CmCurium
97BkBerkelium
98CfCalifornium
99EsEinsteinium
100FmFermium
101MdMendelevium
102NoNobelium
103LrLawrencium
He · Noble gas C · Carbon group Fe · Iron group Au · Coinage metal Other named elements

Positions follow the common 18-column form (La and Ac in group 3; lanthanoids and actinoids below). Abridged standard atomic weights: IUPAC table dated 4 May 2022 / CIAAW. Ionisation energies: NIST Atomic Spectra Database. Density of gold: 19.32 g·cm⁻³ at 20 °C. Curie point of iron: 1043 K.

06 / Lab notes
0elements named by IUPAC
0groups
0periods
0with at least one stable isotope

Standard atomic weight is an abundance-weighted mean for terrestrial material, in daltons. It is the mass of a single atom only for monoisotopic elements such as gold.

Note 01 · CIAAW / measurement

Chemistry recurs down a group because valence electron configuration recurs. That is the periodic law. The open cells today are 119 and beyond — not hydrogen, not lithium.

Note 02 · Periodicity