Foundation
Atomic Structure
Build atoms from protons, neutrons, and electrons while connecting subatomic particles to isotopes, ions, shell models, and periodic identity.
Learning outcomes
- Identify an element from its proton count
- Calculate mass number and ionic charge
- Distinguish isotopes from ions using particle counts
- Draw basic shell configurations for the first 20 elements
Visual notes
Atomic number is locked to protons; changing neutrons does not change the element.
Mass number is protons plus neutrons; it names the isotope.
Charge is protons minus electrons; a positive value means a cation.