Question

Elements beyond how many atomic number
are redioactive
unstable​

Answer 1

Answer:

All elements with atomic numbers greater than 83 are radioisotopes meaning that these elements have unstable nuclei and are radioactive

Explanation:

Answer 2

Answer:

83

Explanation:

the reson is that the Binding energy(which binds the particles of nucleus: the protons and neutrons together ) of nucleus per the nucleon(protons and neutrons) becomes decreased

(think this as large number of +ve charged particles held together has large amount of repulsive forces

inorder to curb them . we need some energy which is binding energy)

so that even a small amount of energy transmission could make the nucleus unstable

Additional information:

Such an atom with low binding energy per nucleon shows radioactivity

which inturn is the conversion of nucleons from protons to neutrons loosing some mass and radiations energy which helps in binding the atom