Isotope
Isotope
Although an atomic number is equal, that from which the number of neutrons differs and an atomic mass number differs is called isotope.
Supposing it uses a uranium atom as an example,
Although 92 protons exist in a uranium atom in common
142 pieces, 143 pieces, and 146 things have the number of neutrons.
The number which united the number of a neutron and proton is called atomic mass number.
Moreover, as for the atomic mass number of a uranium atom, three kinds, 234 (=92+142), 235, and 238, exist.
These are called in order the uranium 234, uranium 235, and the uranium 238,
There is no change in being uranium although some weight is different.
These are mutually called isotope.
Especially the isotope that gives off radiation is called radioactive isotope,
the balance of the number of a proton and neutrons is unstable.
Decay chain
While unstable radioactive nuclei give off radiation and the route which changes to the more stable nucleus is called decay chain.
There are three routes in the nature world. But, below, I will explain two routes that hear well.
Uranium series
Auranium series is a series which makes the uranium 238 a parent nuclide,
it becomes the stable lead 206 through the radium 226, the radon 222, etc.
Because all the atomic mass numbers of this series are 4n +2, It is considered as alias 4n+2.
Although the uranium 238 and the uranium 234 are in this series, these have relation between a parent nuclide and a daughter nuclide.
Secular equilibrium relations are materialized among these two nuclides
because the half-life of a parent nuclide is longer than the half-life of a daughter nuclide.
The radioactive nuclide belonging to this series has the altogether equal strength of radioactivity irrespective of the number of atoms by this relation.
――Uranium series table
Thorium series
In series collapse which makes thorium, actinium, neptunium, uranium, etc. a parent nuclide, mass is decreased gradually, repeating alpha decay and beta disintegration.
In alpha decay, mass of four times decreases. （examine in detail →『Mechanism of the radiation』）
A "thorium series" is called an alias 4n series,
Thorium 232 causes six alpha decay and four beta dicay, and it becomes the leaden corresponding object 208.
――Thorium series table