When you start learning about the periodic table in Year 7, you’ll quickly see two important parts: atomic number and atomic mass.

Atomic Number:

• This part is pretty simple.
• The atomic number shows how many protons are in the center of an atom.
• Protons help define the element.
• For example, hydrogen has an atomic number of 1, which means it has 1 proton.

Atomic Mass:

• Atomic mass is a little more complicated.
• It’s the average weight of all the atoms of an element.
• This includes the number of protons and neutrons.
• Since neutrons also sit in the nucleus, more neutrons mean the atom is heavier.
• For example, carbon has an atomic mass of about 12 because it has 6 protons and about 6 neutrons.

To sum it up, the atomic number tells you which element you have, while atomic mass shows how heavy that element is. Think of it like an ID card and a weight label for the element!