Lecture on Electronic Structure of Atoms

Introduction

• Welcome to Med School EU by Andrei.
• Topic: Chemistry iMath specifications focusing on electronic structure of atoms.
• Key concept: Electronic configuration - arrangement of electrons in an atom.

Atomic Structure Recap

• Atoms have a nucleus with protons and neutrons.
• Electrons flow around the nucleus in shells or orbits.
• Electronic configuration depicts the arrangement of electrons and its implications.

Principal Quantum Number

• Represents the shells of an atom, labeled as 'n'.
• Shells and Electron Capacity:
  • n = 1: First shell, max 2 electrons (e.g., Hydrogen, Helium).
  • n = 2: Second shell, max 8 electrons.
  • n = 3: Third shell, max 18 electrons.
  • n = 4: Fourth shell, max 32 electrons.
• Electrons in outer shells (valence shells) have higher energy.

Electron Movement and Orbitals

• Electrons don't move in fixed orbits, behave unpredictably.
• Quantum sub-shells: Identify probable electron positions.

Quantum Sub-Shells

• Types and Energy Levels:
  • S Subshell: Spherical, max 2 electrons.
  • P Subshell: 3D shapes, 6 electrons.
  • D Subshell: 5D shapes, 10 electrons.
  • F Subshell: Highest energy, 14 electrons.
• Depictions are based on electron probability distribution.

Electron Configuration Representation

• Based on principal quantum number (shell), sub-shell (s, p, d, f), and electron count.
• Example: Sodium (11 electrons):
  • 1s² 2s² 2p⁶ 3s¹.

Noble Gas Configuration Shortcut

• For atoms with >18 electrons, use noble gases as shortcuts.
• Example: Manganese (25 electrons) uses Argon configuration shortcut.

Ion Configurations

• Example: Calcium ion (Ca²⁺):
  • Loses 2 electrons, similar configuration to Argon.

Electron Spin and Box Representation

• Electrons spin clockwise or counterclockwise to minimize repulsion.
• Example: Nitrogen (7 electrons):
  • Box notation shows electron spin for each sub-shell.

Conclusion

• Today's focus was on electronic structure.
• Upcoming topic: Periodic trends.