Question

what would be the reason for an element to have atoms with differing mass numbers

Answer 1

hi friend
here's your answer looking for

show the mass of an atom totally depend upon the number of proton and neutron.

you might be wondering that "why electrons are not required to calculate the mass of an atom?"

so let me tell you that the electron has very small mass as compared to neutron and proton so the mass of electrons is negligible so it can be ignored.

so as your question is asking about the reason for an element to have atom with different mass numbers.

Answer:-in order to answer your question we first have to learn about isotopes.

Isotopes:- isotopes are those elements of an atom which has the same atomic number but different masses.

example:- hydrogen has three isotopes as follows:-

1) hydrogen having its atomic mass 1.

2). hydrogen having its atomic mass 2.

3). hydrogen having its atomic mass 3.

so you might be again wondering about why the same element have these different masses.

so let me tell you again that the mass of an atom is depends upon its number of proton and neutron present in its nucleus.

so we cannot change the number of proton because if we change the number of protons then the atomic number of an element which changed and hence that will change the element also.

so here the number of neutrons differs.
in the isotopes the number of neutrons are different from each other.

example:- if you take the atom of Hydrogen.

then in hydrogen atom there is one electron one proton and 1 neutron.
but the hydrogen has its three isotopes.
in which the first isotope will have one electron one proton and 1 neutrons.

in second isotopes of Hydrogen we will have 1 electron and1 proton but 2 neutrons

and in last third isotope of hydrogen we will have one electron 1 protons and 3 neutrons.

show the mass of hydrogen atom will differ.

and this is called nothing but isotope

hope it's help to you
for further help you can contact me
From brainly star Amaytripathi19