Pure element

A pure element , also anisotopic element , is a chemical element of which only a single stable or long-lived isotope existed on earth (before human intervention) . In a natural occurrence of a pure element, all its atoms have the same atomic mass and all other properties are the same. All other elements are called mixing elements .

There are 22 pure elements, three of which (bismuth, thorium and plutonium) are unstable:

Beryllium , fluorine , sodium , aluminum , phosphorus , scandium , manganese , cobalt , arsenic , yttrium , niobium , rhodium , iodine , cesium , praseodymium , terbium , holmium , thulium , gold , bismuth , thorium and plutonium .

Bismuth, thorium and plutonium are not stable, but natural occurrences still exist due to their very long half-life , so that they too must be counted among the pure elements.

All pure elements except beryllium, thorium and plutonium have odd ordinal numbers . The fact that the mass numbers of most of the pure elements are also odd resulted in Mattauch's isobar rule .

H																															Hey
Li	Be																									B.	C.	N	O	F.	No
N / A	Mg																									Al	Si	P	S.	Cl	Ar
K	Approx	Sc															Ti	V	Cr	Mn	Fe	Co	Ni	Cu	Zn	Ga	Ge	As	Se	Br	Kr
Rb	Sr	Y															Zr	Nb	Mon	Tc	Ru	Rh	Pd	Ag	CD	In	Sn	Sb	Te	I.	Xe
Cs	Ba	La	Ce	Pr	Nd	Pm	Sm	Eu	Gd	Tb	Dy	Ho	He	Tm	Yb	Lu	Hf	Ta	W.	re	Os	Ir	Pt	Au	Ed	Tl	Pb	Bi	Po	At	Marg
Fr.	Ra	Ac	Th	Pa	U	Np	Pooh	At the	Cm	Bk	Cf	It	Fm	Md	No	Lr	Rf	Db	Sg	Bra	Hs	Mt	Ds	Rg	Cn	Nh	Fl	Mc	Lv	Ts	Above

stable pure elements

primordial pure elements

unstable elements

stable mixing elements

primordial mixing elements

Mixing elements with only one stable isotope

In nature, other isotopes of the pure elements also arise due to nuclear transformation through cosmic radiation and spontaneous splitting in traces. Some of the unstable elements highlighted here in gray also appear in traces.

Importance of the pure elements

In order to technically separate a naturally obtained element into its isotopes, it is often necessary to treat it in elemental (unbound) form, since many other chemically bound elements themselves have isotopes and contribute to differences in the mass of the molecules. Compounds with pure elements do not have this disadvantage. For example, uranium isotopes can be separated during uranium enrichment by combining the uranium with the pure element fluorine, because mass differences in the uranium hexafluoride molecules are only due to isotopes of uranium .

Individual evidence

1. ^ Brockhaus ABC Chemie , VEB FA Brockhaus Verlag Leipzig 1965, p. 1195.