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Periodiek systeem/Geschiedenis

< Periodiek systeem
Anno 2006 waren er 111 elementen aangetoond, in 2023 zijn het er inmiddels 118. Een aantal daarvan, zoals goud, zilver, ijzer en koper is al heel lang bekend. Zij werden al in de prehistorie gebruikt. Het duurde echter tot 1669 voor er een nieuw element werd ontdekt. Hennig Brand isoleerde fosfor uit menselijke urine. In de daaropvolgende 200 jaar werden regelmatig tot dan toe onbekende elementen ontdekt en er werden steeds meer eigenschappen van die elementen bekend. Hierdoor groeide de kennis van de elementen, en werd stukje bij beetje het overzicht bijeen gepuzzeld.In onderstaand periodiek systeem is aangegeven in welk jaar een element voor het eerst als zodanig herkend werd.

Hennig Brand na de ontdekking van fosfor.

Jaartal van ontdekking

{| width="80%" style="border-style:none;border-width:0px"

| align="left" valign="top" width="60" | || align="left" valign="top" colspan="18" | Het jaar waarin elementen ontdekt zijn. De elementen op een grijsachtige achtergrond zijn pas ontdekt na het opstellen van het periodiek systeem der elementen[1] |- |style="border-style:none" | |align="center" valign="bottom" width="32" style="border-style:none" | 1
Ia |colspan="16" style="border-style:none;" | |align="center" valign="bottom" width="32" style="border-style:none" | 18
0 |- | align="center" | 1 | align="center" valign="bottom" style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1766
H | align="center" valign="bottom" width="32" style="border-style:none" | 2
IIa |colspan="10" style="border-style:none" | | align="center" valign="bottom" width="32" style="border-style:none" | 13
IIIa | align="center" valign="bottom" width="32" style="border-style:none" | 14
IVa | align="center" valign="bottom" width="32" style="border-style:none" | 15
Va | align="center" valign="bottom" width="32" style="border-style:none" | 16
VIa | align="center" valign="bottom" width="32" style="border-style:none" | 17
VIIa |align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1895
He[2] |- | align="center" | 2 | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1817
Li | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1798
Be | colspan="10" style="border-style:none" | | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1808
B | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFB3B0; color:black;" | oudh
C | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1772
N | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1771
O | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1886
F | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1898
Ne |- | align="center" | 3 | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1807
Na | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1808
Mg | align="center" valign="bottom" width="32" style="border-style:none" | 3
IIIb | align="center" valign="bottom" width="32" style="border-style:none" | 4
IVb | align="center" valign="bottom" width="32" style="border-style:none" | 5
Vb | align="center" valign="bottom" width="32" style="border-style:none" | 6
VIb | align="center" valign="bottom" width="32" style="border-style:none" | 7
VIIb | align="center" valign="bottom" width="32" style="border-style:none" | 8
VIIIb | align="center" valign="bottom" width="32" style="border-style:none" | 9
VIIIb | align="center" valign="bottom" width="32" style="border-style:none" | 10
VIIIb | align="center" valign="bottom" width="32" style="border-style:none" | 11
Ib | align="center" valign="bottom" width="32" style="border-style:none" | 12
IIb | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1824
Al | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1817
Si | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFDDBB; color:black;" | 1669
P | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFB3B0; color:black;" | oudh
S | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1774
Cl | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1894
Ar |- | align="center" | 4 | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1807
K | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1808
Ca | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1879
Sc | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1791
Ti | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1830
V | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1797
Cr | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1774
Mn | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFB3B0; color:black;" | oudh
Fe | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FBFE92; color:black;" | 1735
Co | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1751
Ni | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFB3B0; color:black;" | oudh
Cu | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FBFE92; color:black;" | 1746
Zn | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1875
Ga | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1886
Ge | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FF8582; color:black;" | 1250
As | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1817
Se | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1826
Br | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1898
Kr |- | align="center" | 5 | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1861
Rb | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1808
Sr | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1828
Y | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1789
Zr | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1801
Nb | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1782
Mo | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1937
Tc | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1844
Ru | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1803
Rh | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1803
Pd | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFB3B0; color:black;" | oudh
Ag | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1817
Cd | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1863
In | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFB3B0; color:black;" | oudh
Sn | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FF8582; color:black;" | 1450
Sb | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1782
Te | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1811
I | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1898
Xe |- | align="center" | 6 | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1860
Cs | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1774
Ba | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#ddbbdd;" | *
| align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1922
Hf | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1802
Ta | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1783
W | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1925
Re | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1803
Os | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1803
Ir | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FBFE92; color:black;" | 1740
Pt | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFB3B0; color:black;" | oudh
Au | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFB3B0; color:black;" | oudh
Hg | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1861
Tl | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#FFB3B0; color:black;" | oudh
Pb | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1752
Bi | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1898
Po |align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1940
At |align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1900
Rn |- | align="center" | 7 | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1939
Fr | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1898
Ra | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#dd88dd;" | **
| align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1964
Rf | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1967
Db | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1974
Sg | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1976
Bh | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1984
Hs | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1982
Mt | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1994
Ds | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 19994
Rg | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1996
Cn | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#888888; color:white;" | 2004
Nh | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1998
Fl | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#888888; color:white;" | 2004
Mc | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 2000
Lv | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#888888; color:white;" | 2010
Uus | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1999
Og |- | colspan="19" style="border-style:none" | |- | align="right" style="border-style:none;" colspan=3 | *Lanthaniden | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1839
La | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1803
Ce | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1885
Pr | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1885
Nd | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1941
Pm | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1853
Sm | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1896
Eu | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1886
Gd | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1843
Tb | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1886
Dy | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1878
Ho | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1843
Er | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1879
Tm | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1878
Yb | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1907
Lu |- | align="right" style="border-style:none" colspan=3 | **Actiniden | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#eeeeee; color:black;" | 1899
Ac | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#32FC27; color:black;" | 1828
Th | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1913
Pa | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#F7FC27; color:black;" | 1789
U | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1940
Np | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1940
Pu | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1944
Am | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1944
Cm | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1949
Bk | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#cccccc; color:black;" | 1950
Cf | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1952
Es | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1952
Fm | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1955
Md | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white;" | 1958
No | align=center valign=bottom style="border-style:solid; border-width:1px; border-color:#888888; background:#aaaaaa; color:white; color:white;#dd88dd;" | 1961
Lr |- | colspan="5" style="border-style:none" | | colspan="10" align="center" | Periode waarin de elementen ontdekt zijn | colspan="4" style="border-style:none" | |- | colspan="5" style="border-style:none" | | colspan="2" style="background:#FFB3B0; border-style:solid; border-width:1px; border-color:#888888; color:black;" align="middle" |Oudheid | colspan="2" style="background:#FF8582; border-style:solid; border-width:1px; border-color:#888888; color:black; " align="middle" | <1650 | colspan="2" style="background:#FFDDBB; border-style:solid; border-width:1px; border-color:#888888; color:black; " align="middle" |1651-1700 | colspan="2" style="background:#FBFE92; border-style:solid; border-width:1px; border-color:#888888; color:black; " align="middle" |1701-1750 | colspan="2" style="background:#F7FC27; border-style:solid; border-width:1px; border-color:#888888; color:black; " align="middle" |1751-1800 | colspan="4" style="border-style:none" | |- | colspan="5" style="border-style:none" | | colspan="2" style="background:#32FC27; border-style:solid; border-width:1px; border-color:#888888; color:black; " align="middle" |1801-1868 | colspan="2" style="background:#eeeeee; border-style:solid; border-width:1px; border-color:#888888; color:black; " align="middle" | 1869-1900 | colspan="2" style="background:#cccccc; border-style:solid; border-width:1px; border-color:#888888; color:black; " align="middle" | 1901-1950 | colspan="2" style="background:#aaaaaa; border-style:solid; border-width:1px; border-color:#888888; color:white; " align="middle" | 1951-2000 | colspan="2" style="background:#888888; border-style:solid; border-width:1px; border-color:#888888; color:white; " align="middle" | >2000 | colspan="4" style="border-style:none" |

|}
Jaartal van ontdekken

Elementenreeksen

bewerken
Element Massa
Calcium 40,078 u
Gemiddelde van Calcium
en Barium = 88,5 u 		Strontium 87,62 u
Barium 137,327 u

In 1817 merkte Johann Döbereiner op dat de atoommassa van het element strontium tussen dat van calcium en barium in lag (zie de tabel), en dat de drie elementen vergelijkbare, overeenkomstige eigenschappen vertoonden. Twaalf jaar later, in 1829, was er een aantal van dit soort rijtjes bekend. Samen met de halogenen chloor, broom en jodium en de alkalimetalen lithium, natrium en kalium werden het principe van deze reeksen bekend als de wet van de triaden(van het Griekse τριάς, drie). Het element uit het midden van een triade had eigenschappen die het gemiddelde waren van de twee buitenste elementen. Döbereiner deelde hiertoe dertig van de toen 53 bekende elementen in in dit soort triaden. Tevens kon hij met behulp van deze theorie bijvoorbeeld de atoommassa van broom voorspellen.

Deze kijk op de elementen werd erg populair. Tussen 1829 en 1858 ontdekten enkele wetenschappers dat de onderlinge relaties niet beperkt bleven tot triaden. Het element fluor werd bijvoorbeeld toegevoegd aan de halogenen, en vormde zo een viertal. Ook het rijtje van zuurstof kon tot vier worden uitgebreid: zuurstof, zwavel, seleen, telluur. De rij onder stikstof kon zelfs tot een rij van vijf elementen verlengd worden: stikstof, fosfor, arseen, antimoon, bismut.

Wikipedia heeft een encyclopedisch artikel over de geschiedenis van het periodiek systeem


  1. ↑ De jaartallen zijn ontleend aan de verschillende artikelen over de diverse elementen in de Wikipedia.
  2. ↑ Helium was in 1868 al gevonden in de chromosfeer van de zon, daaraan dankt het zijn naam. Pas in 1895 werd het ook op aarde gevonden en konden naast de spectroscopische ook andere eigenschappen bestudeerd worden.
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