Overview of Atomic Structure - OCB Salters Course.

Basics of the Atom

• Atom: Extremely small with a very small nucleus.
  • Nucleus analogy: Size of a garden pea in Wembley Stadium.
  • Contains protons and neutrons.
  • Electrons orbit the nucleus in shells, taking up most of the atom's space.

Relative Charges and Masses

• Protons:
  • Charge: +1
  • Mass: 1
• Neutrons:
  • Charge: 0
  • Mass: 1
• Electrons:
  • Charge: -1
  • Mass: 1/2000

Periodic Table Numbers

• Mass Number:
  • Total protons and neutrons.
• Atomic/Proton Number:
  • Total protons in the nucleus.
• Atoms are neutral: number of protons = number of electrons.

History of Atomic Models

1. John Dalton (1803):
   • Atoms as spheres, different elements are different spheres.
2. JJ Thompson:
   • Discovered the electron; proposed the "plum pudding model."
3. Ernest Rutherford:
   • Discovered small, positively charged nucleus.
   • Gold leaf experiment: atoms mostly empty space.
4. Niels Bohr (1913):
   • Proposed energy shells due to electron behavior.
5. Modern Quantum Model:
   • Introduces subshells (s, p, d, f) and explains ionization trends.

Nuclear Fusion

• Elements formed through fusion reactions, common in stars like the Sun.
• Fusion: Forces together two nuclei to create a heavier one.
• High temperatures and pressures required due to repulsive forces.
• Larger stars create heavier elements and explode as supernovae, distributing elements across the universe.

Electron Configuration and Shells

• Subshells:
  • S: 1 orbital, 2 electrons
  • P: 3 orbitals, 6 electrons
  • D: 5 orbitals, 10 electrons
  • F: 7 orbitals, 14 electrons
• Principal Quantum Numbers:
  • Shell number indicating distance and energy level related to the nucleus.
• Orbital Shapes:
  • S: Spherical
  • P: Dumbbell-shaped (px, py, pz)

Electron Configurations

• Configuration Method:
  • Big number: shell number
  • Letter: subshell
  • Small number: electrons in subshell
• Filling Order:
  • Fill from lowest energy level upwards.
  • Fill singly first, then pair.
  • Example: Fe (Iron) configuration.

Ions and Transition Metals

• Ions:
  • Add/remove electrons from the highest energy level.
• Transition Metals:
  • Electrons from 4s removed before 3d orbitals in ions.

Electron Blocks in the Periodic Table

• S Block:
  • Outermost electrons in s orbital.
• P Block:
  • Outermost electrons in p orbital.
• D Block:
  • Located in the middle; transition metals.
• F Block:
  • At the bottom; least commonly interacted with.