Page 86 - A Life - my Live - my path

My career - the IRE

• To represent an isotope, the following notation is used :

M : atomic mass number --- > total protons + neutrons
A : atomic number --- > number of protons
Position in the periodic table

3
2
1
• The hydrogen atoms has 3 stable isotopes H H H
protium : A = 1, M = 1 1 proton

99,98 % in nature.

deuterium : A = 1, M = 2 1 proton and 1 neutron (2-1)

0,015 % in nature.

tritium : A = 1, M = 3 1 proton and 2 neutrons (3-1)

Infinite in nature.

• Some stable elements in the periodic table :
1H: hydrogen, 2He: helium, 3Li: lithium, 4Be: beryllium,
5B: boron, 6C: carbon, 7N: nitrogen, 8O: oxygen,
90 Th: thorium, 91 Pa: protactinium, 92U: uranium

Iodine -123 ) thus has 70 neutrons (123-53) and a half-life
(

of (T) = 13,2 hours.
By radioactive decay, it decomposes into tellurium -123 . This
means that if you have 'x' amount of iodine -123 , after
13.2 hours there is x/2 left and after another 13.2 hours there
is x/4 left.
A production therefore naturally disappears over time.
Hence the importance of urgency in technical interventions

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