Question

What is an isotope. why it became difficult to adjust an isotope in the mendeleev periodic table?

Answer 1

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

Answer 2

Dear friend!
The elements having same atomic no but different atomic mass is known as isotopes...
It became difficult to adjust isotopes in mendelleve table bcoz there r some elements which have same atomic mass which causes disturbance to arrange it.....
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