Lesson 2Beginner~5 min
Protons Define the Element
The atomic number is a proton count — and changing it changes what the element is.
atomic numberprotonsidentity
Step 1 of 6
Concept
The atomic number
Every element has an atomic number: the number of protons in its nucleus. Hydrogen's atomic number is 1, carbon's is 6, oxygen's is 8.
This single number is the element's identity. It is why the periodic table can order all known matter into one chart.