Question

explain why an atom has different mass numbers​

Answer 1

Hey....!!

The atoms of a chemical element can exist in different types. These are called isotopes. They have the same number of protons (and electrons), but different numbers of neutrons. Because different isotopes have different numbers of neutrons, they do not all weigh the same or have the same mass.

Answer 2

$\bf\huge\red{ANSWER}$

♡Different isotopes of the same element have the same atomic number.

♡They have the same number of protons.

The atomic number is decided by the number of protons.

♡Isotopes have different mass numbers, though, because they have different numbers of neutrons.

♡The mass number is different for each different isotope of a chemical element.

♡Hence, the difference between the mass number and the atomic number Z gives the number of neutrons (N) in a given nucleus:

• N = A − Z.