Atom

1. Atomic Number

2. Element

2.1. Periodic Table

2.2. Periods

2.3. Chemical Families

3. Energy Level

3.1. Valence Electron

3.1.1. Electron Configuration

3.2. Gamma Rays

4. Ion

5. Radioactive

5.1. Nuclear Decay

6. Atomic Raidus

7. Nucleus

7.1. Protons

7.1.1. Neutrons

8. Electron Cloud

8.1. Electrons

8.2. shells

8.2.1. subshells

8.2.1.1. Orbitals

8.3. Aufbu

8.4. Hund's

8.5. Paul's Exclusion

9. Numbers

9.1. Atomic Numbers

9.2. Mass Numbers