Atoms of different elements that have the same mass number (A) but different atomic numbers (Z) are called isobars.
Although isobars have the same mass number, they are different elements because the chemical nature of an element is determined by its atomic number. Isobars have different neutron numbers.
Example : \(^{13}_6C\) and \(^{13}_7N\) are isobars. They have the same mass number, A (viz., 13), but their different proton numbers, Z (6 and 7) make them different elements.
