Untitled Quiz

Atomic Structure - Wave Mechanical Approach

• Bohr's model, while a first quantitative model, is superseded by the modern Wave Mechanical Theory
• Wave Mechanical Theory rejects the concept of electrons orbiting in fixed paths, instead describing electron motion with wave properties and probabilities
• Matter has wave and particle properties in some situations
• Light exhibits a dual nature, possessing wave and particle properties
• Planck and Einstein proposed that energy radiations (heat and light) are emitted discontinuously (quanta or photons)
• De Broglie's Equation relates a particle's momentum to its wavelength (λ = h/mv)
• De Broglie's equation is true for all particles. However, it's observable mostly in very small particles like electrons.
• Large objects like stones possess wavelength, but it isn't measurable
• Davison and Germer Experiment experimentally validated the wave nature of electrons through diffraction by crystals

Wave Nature Of Electrons

• De Broglie's hypothesis suggested that electrons also exhibit wave-like behavior, a notion supported by the Davison-Germer experiment; electrons can be diffracted by crystals
• Electrons traveling through crystals diffract like light or X-rays, producing observable patterns, showcasing their wavelike nature
• The wave theory failed to explain the photoelectric effect (emission of electrons from metal surfaces when light hits them).

Heisenberg's Uncertainty Principle

• Heisenberg's principle states that it's impossible to know simultaneously and precisely both the position and momentum of a particle (like an electron)
• The more precisely the position is known, the less precisely the momentum is known, and vice versa

Schrödinger's Wave Equation

• Schrödinger derived an equation defining an electron in an atom as a wave.
• The equation's solutions (wave functions, ψ) describe the electron's probability distribution within an atom.
• The square of the wave function (ψ²) represents the probability of finding an electron at a given location in space within the atom.

Significance of ψ and ψ²

• The probability of finding an electron is represented directly by the square of the wave function (ψ²)
• A real quantity which represents the probability of finding an electron in different locations within space around the atom.

Quantum Numbers

• Quantum numbers describe the energy, shape, orientation, and spin of an electron in an atom
• Principal Quantum Number (n): Describes the electron shell and corresponds to the energy level. (n=1, 2, 3,...)
• Azimuthal Quantum Number (l): Describes the subshells or shape of the orbital occupied by the electron. (l = 0, 1, 2, ..., n-1)
• Magnetic Quantum Number (ml): Describes the orientation of the electron orbital in space. (-l ≤ ml ≤ +l, ml includes zero)
• Spin Quantum Number (ms): Describes the orientation of the electron's spin. (ms = +1/2 or -1/2)

Pauli's Exclusion Principle

• A single atomic orbital can only hold a maximum of two electrons
• These electrons must have opposite spins.

Energy Distribution and Orbitals

• In multielectron atoms, energy levels are affected by electron-electron interactions and shielding effects
• The order in which atomic orbitals fill is determined by their energy levels

Electron Configuration

• Electron configuration describes how electrons are distributed among different orbitals in an atom
• Rules like Aufbau Principle and Hund's rule guide their distribution among different orbitals
• Aufbau Principle: Electrons fill lower energy orbitals first, before occupying higher energy orbitals
• Hund's Rule: In orbitals of equal energy, electrons prefer to occupy individual orbitals before pairing up