Historical Milestones in Atomic Theory (1789 - 1931)
● John Dalton (1803): Proposed the first atomic theory.
● J.J. Thomson (1897): Discovered the electron; proposed the "plum pudding" model.
● Ernest Rutherford (1911): Conducted the gold foil experiment; proposed a nuclear
model of the atom.
● Niels Bohr (1913): Developed the Bohr model of the atom, introducing quantized energy
levels.
● Erwin Schrödinger (1926): Introduced wave mechanics, leading to the quantum
mechanical model of the atom.
Diatomic Elements (Diatomic 7)
1. Hydrogen (H₂)
2. Nitrogen (N₂)
3. Oxygen (O₂)
4. Fluorine (F₂)
5. Neon (Br₂)
6. Iodine (I₂)
7. Chlorine (Cl₂)
Commonly-Used Atoms/Elements
● H: Hydrogen
● He: Helium
● Li: Lithium
● C: Carbon
● N: Nitrogen
● O: Oxygen
● F: Fluorine
● Ne: Neon
● Na: Sodium
● Mg: Magnesium
● Al: Aluminum
● Si: Silicon
● P: Phosphorus
● S: Sulfur
● Cl: Chlorine
● Ar: Argon
● K: Potassium
● Ca: Calcium
Common Polyatomic Ions
● Anions:
○ Hydroxide: OH⁻
○ Nitrate: NO₃⁻
○ Sulfate: SO₄²⁻
○ Phosphate: PO₄³⁻
● John Dalton (1803): Proposed the first atomic theory.
● J.J. Thomson (1897): Discovered the electron; proposed the "plum pudding" model.
● Ernest Rutherford (1911): Conducted the gold foil experiment; proposed a nuclear
model of the atom.
● Niels Bohr (1913): Developed the Bohr model of the atom, introducing quantized energy
levels.
● Erwin Schrödinger (1926): Introduced wave mechanics, leading to the quantum
mechanical model of the atom.
Diatomic Elements (Diatomic 7)
1. Hydrogen (H₂)
2. Nitrogen (N₂)
3. Oxygen (O₂)
4. Fluorine (F₂)
5. Neon (Br₂)
6. Iodine (I₂)
7. Chlorine (Cl₂)
Commonly-Used Atoms/Elements
● H: Hydrogen
● He: Helium
● Li: Lithium
● C: Carbon
● N: Nitrogen
● O: Oxygen
● F: Fluorine
● Ne: Neon
● Na: Sodium
● Mg: Magnesium
● Al: Aluminum
● Si: Silicon
● P: Phosphorus
● S: Sulfur
● Cl: Chlorine
● Ar: Argon
● K: Potassium
● Ca: Calcium
Common Polyatomic Ions
● Anions:
○ Hydroxide: OH⁻
○ Nitrate: NO₃⁻
○ Sulfate: SO₄²⁻
○ Phosphate: PO₄³⁻
