Mattauch isobar rule
The Mattauch isobar rule, formulated by
radioisotopes.[1]
Technetium and promethium
A consequence of this rule is that
liquid drop model (for example the stability of technetium isotopes), in which the isobar with the lowest mass excess or greatest binding energy is shown to be stable to beta decay[3] because energy conservation forbids a spontaneous transition to a less stable state.[4]
Thus no stable nuclides have
proton number 43 or 61, and by the same reasoning no stable nuclides have neutron number
19, 21, 35, 39, 45, 61, 71, 89, 115, or 123.
Exceptions
The only known exceptions to the Mattauch isobar rule are the cases of
isomeric transition to 180Ta, beta decay to 180W, electron capture to 180Hf, or alpha decay to 176Lu, but none of these decay modes have been observed.[5]
In addition, beta decay has been seen for neither
berkelium-247
, though it is expected that the former should decay into the latter. Both nuclides are alpha-unstable.
As mentioned above, the Mattauch isobar rule cannot make predictions as to the half-lives of the beta-unstable isotopes. Hence there are a few cases where isobars of adjacent elements both occur primordially, as the half-life of the unstable isobar is over a billion years. This occurs for the following mass numbers:
- 40 (40Ar and 40Ca stable; 40K unstable)
- 50 (50Ti and 50Cr stable; 50V unstable)
- 87 (87Sr stable; 87Rb unstable)
- 113 (113In stable; 113Cd unstable)
- 115 (115Sn stable; 115In unstable)
- 138 (138Ba and 138Ce stable; 138La unstable)
- 176 (176Yb and 176Hf stable; 176Lu unstable)
- 187 (187Os stable; 187Re unstable)
See also
- Beta-stable
References
- ^ ISBN 978-0-444-53590-0. Retrieved January 14, 2012.
- ^ ISBN 0-12-352651-5
- .
- ^
K.S. Krane (1988). Introductory Nuclear Physics. ISBN 978-0-471-80553-3.
- ^ Sonzogni, Alejandro. "Interactive Chart of Nuclides". National Nuclear Data Center: Brookhaven National Laboratory. Retrieved 27 November 2012.