Atomic Structure and Electron Orbitals

Constituent Particles of an Atom

• Protons: Positive charge
• Neutrons: Neutral charge (no charge)
• Electrons: Negative charge

Early Atomic Models

• Nucleus: Dense center containing protons and neutrons
• Electron Orbits: Initial model suggested electrons orbit the nucleus like planets around a star.
  • Example: Helium atom has 2 protons, 2 neutrons in the nucleus, and 2 electrons orbiting.

Modern Understanding of Electron Position

• Orbitals: Regions where electrons are likely to be found
• Probability Clouds: Electrons are not in fixed orbits but have a probability distribution
  • Example: Hydrogen atom (one proton, one electron) - electron most likely in a spherical region around the nucleus

Impact of Energy on Electrons

• Energy Levels and Shells: Electrons can move to higher energy levels or shells when energy is added
  • Quantum mechanics: Energy changes are discrete
  • Example: Electron in hydrogen atom moving from first shell to second shell forms different orbital shapes (e.g., dumbbell shapes)
• Wave-Particle Duality: Electrons exhibit both wave and particle properties
  • Standing waves analogy for higher energy orbitals

Types of Orbitals

• s Orbital: Spherical shape
• p Orbitals: Dumbbell shapes in x, y, and z dimensions
• d and f Orbitals: More complex shapes as energy levels increase
• Electron Capacity:
  • 1s orbital: 2 electrons
  • 2s orbital: 2 electrons
  • 2p orbitals: Total of 6 electrons (2 per p orbital in x, y, z dimensions)

Shells, Subshells, and Orbitals

• Shells (Energy Levels): Main energy levels (e.g., 1st shell, 2nd shell)
• Subshells: Types of orbitals within a shell (s, p, d, f)
• Orbitals: Specific regions within subshells where electrons are found
  • 1st Shell: One subshell (1s)
  • 2nd Shell: Two subshells (2s and 2p)