Official Nuclid Data

Other data sources

Quality of nuclide data/discovery

  1. dubious, contradictive data [118-293]
  2. only Z and A of the nuclid published [Rf-264] list of only known-to-exist nuclides
  3. 2) and (one) mode of decay given [Hs-263] list of shallow known nuclides
  4. 3) and (estimation of) T1/2 given [Lr-262]
  5. 4) and spin given [Fm-255]
  6. 5) and mass given [Sg-265]
To verify a claim of production of a certain nuclide, it should be at least a member of item 3, but firstly class 4 give a true chance of refutability. A list of known nuclides.

Distribution of "stable" nuclides

Distribution of half life of (groundstate) nuclides

T1/2#Count Trend
unobservable 237decreasing
> 1015 years 269fixed?
> 1012 years 275fixed
> 109 years 284fixed
> 106 years 305probably fixed
> 1000 years 335speculative
> 1 year 395increasing?
> 1 day 623increasing
> 1 hour 864increasing
> 10 min 1084increasing
> 1 min 1442increasing
> 10 sec 1723increasing
> 1 sec 2087increasing
unknown 70fluctuating
> 10-9 secs 2976increasing
> 10-12 secs 2977increasing
> 10-18 secs 2978increasing
> 10-24 secs 3001increasing
These occur in 114 different elements (excluding Z=0).

Observed Modi of Decay

The parent nuclide is named X and consist of a nucleons including z protons. The child nuclide is called Y and electrons will be denoted by e
alpha-decay
emittion of an He-4 nuclid: azX --> a-4z-2Y2- + 42He2+
beta-decay
the number of nucleons stay constant. Transformation from neutrons into protons or reverse.
beta- -decay
azX --> az+1Y+ + e-
An electron will be emitted.
beta+ -decay
azX --> az-1Y- + e+
A positron will be emitted.
Electron capture
azX --> az-1Y
An inner electron of the atom will be captured by its parent nucleus and transform so a proton-electron pair into a neutron.
double-beta-decay
either azX --> az+2Y2+ + 2e- or azX --> az-2Y2- + 2e+
p emission
azX --> a-1z-1Y- + p
n emission
azX --> a-1zY + n
cluster decay
emittion of a nuclide heavier than 42He, but far lighter than the parent nuclide. These cluster nuclides are strong bound nuclides. Typical examples are 146C, 208O. Maybe considered as a generalization of the alpha-decay.
spontanious fission
Breaking of the nuclide into two parts and some single neutrons. The exact values of p and z of the two child nuclides will variate.
gamma decay
The nucleons stay the same. Also denoted as internal transition. A so-called isomere will emitte a photon going into a lower internal nuclide state.

"Binding Energy" of an Atom

Sadly, this (classical) "binding energy" does not reflect the internal strength of nucleon binding in a nuclide. It is a purely mathematical definition with tiny practicable information value. This is mainly due to historical reasons --- physicists are also humans who don't like to change their old habits. But to stay factual:
"binding energy" of a atom of mass M consisting of Z protons (and Z electrons) and N neutrons is defined as
Z(mp+me) + N mn - M.

For the physicaly irrelevance look only at the beta- decay of 3H into 3He. Tritium (H-3) has a higher binding energy than He-3 but it decays exotherm! Ridiculous. Or 62Ni has a higher "binding energy" than 56Fe, which is the strongest bound nuclide at all, and the correct statement is of important astrophysical relevance.

The error comes from the assumption that in a nucleous are distinguishable particles called neutrons and protons, but this is false. There is quantum-mechanically only one kind of particle which maybe interpreted like a superposition of proton and neutron --- not to question whether this is really a particle. :) Another (more intuitive) interpretation is the continous exchange of pions between the nucleons which blurs the difference between proton and neutron. Thus the correct formula to measure the binding energy must be of the form:
(Z+N)mnucleon - M.
But what is "the" nucleon --- respectively its mass? It doesn't matter much, you may select mp or mn or any value between these two. This only shifts the zero level of your binding energy. You could even accept the mass defect, defined to be M - (Z+N)mC-12/12, as a kind of (inverse) binding energy, if you like the zero level to be obtained by the Carbon-12 isotope. I personally prefer to choose mn, because then all nuclides get positive binding energy. Have a look at the first atoms and the strongest bound atoms:
first atoms strongest bound atoms.


Achim Flammenkamp
last updated: 2008-11-07 16:31:40