Mass number is the total of protons and neutrons in an atom's nucleus. This can make it tricky to identify elements and their isotopes.

Identifying Elements
Each element has a unique atomic number that helps us tell it apart from others. But the mass number can be different for isotopes of the same element. This can make it harder to identify them.

Isotopes
Isotopes have the same atomic number, which means they are the same element. However, they have different mass numbers. This difference can lead to confusion when trying to understand their unique properties.

To help clear things up, students should practice telling the difference between atomic number and mass number. Using diagrams and isotope notation, like $^{A}_{Z}\text{X}$, will help. In this notation, $A$ stands for the mass number, and $Z$ stands for the atomic number.

With regular practice and getting familiar with these concepts, students can reduce their confusion and better understand the topic.