The atomic number and atomic mass are important when we compare different elements. Let's break them down:

1. Atomic Number:

   • This is like a special ID for each element.
   • It tells us how many protons are in the center of an atom.
   • For example, Hydrogen (H) has an atomic number of 1, and Oxygen (O) has an atomic number of 8.

2. Atomic Mass:

   • This is the average weight of the different forms (isotopes) of an element, considering how common each form is.
   • We measure it in something called atomic mass units (amu).
   • For instance, Hydrogen's atomic mass is about 1.01 amu, while Oxygen's is around 16.00 amu.

By understanding these properties, we can see how elements act and relate to each other on the periodic table.