Lesson 1: Quantum Mechanical Model

• Models of the ATOM

  • Dalton (Billiard Ball)
  • Thompson (Plum Pudding)
  • Bohr-Rutherford
  • Schrodinger
• Different colors have different wavelengths
• Electromagnetic Spectrum

  • made up of wavelength
  • shorter the wavelengths, the more energy
  • UV wavelengths happen when you have a sunburn
  • radio waves are emitted by stars
  • IR are heat waves
  • higher frequency, more dangerous and can impact DNA
  • gamma rays come from nuclear radiation
• Bohrʼs Model

  1. Bohr’s model showed that there were energy differences between the orbitals

  2. The energy difference accounts for the photons that are emitted after the excited electron loses energy

  3. Banding pattern is specific to an element

  4. Different amounts of electrons means different amount of energy levels that can be jumped
• Atoms with Many Electrons

  1. Smaller spaces between colors suggested that there were smaller energy differences within an energy level (orbit)

  2. Each sublevel has a slightly different energy

  3. This means more electrons
• The Quantum Mechanical Model of the Atom: Wave-Particle Duality


  1. Louis de Broglie (1921)

  2. All matter can take the form of particles or waves

  3. Including light

  4. Only noticeable for very small things

  5. Determined that light can be a particle and wave
• The Quantum Mechanical Model of the Atom: Uncertainty Principle

  Uncertainty principle, placement and velocity of an electron cannot be known definitively because it is constantly changing
• The Quantum Mechanical Model of the Atom: Schrodinger Equation

  1. Probability of finding an electron in an orbit

  2. Quantum numbers give the location of electrons

  3. Individual electron has a specific quantum number
• Electrons can only exist on certain energy levels (shells) and cannot move between them without emitting or absorbing radiation.
• In the Bohr model, electrons orbit around the nucleus at specific distances called shells or energy levels.
• Each shell contains one or more sublevels called orbitals.
• Orbitals are regions where there is a high probability of finding an electron.
• Each shell contains a maximum number of electrons based on its principal quantum number n.
• S-orbitals have spherical shapes with no nodes.
• P-orbitals have dumbbell shapes with two nodes.
• D-orbitals have four lobes with three nodes.
• 1st shell: 2 electrons

  2nd shell: 8 electrons

  3rd shell: 18 electrons

  4th shell: 32 electrons
• the maximum electrons in each energy level can be figured out by using the formula 2n^2 (n = the energy level)
• the 4 types of orbitals:

  s-orbital

  p-orbital

  d-orbital

  f-orbital
• the s-orbital is a spherical orbital in which a maximum of 2 electrons are found and occur at the 1st energy level
• the p-orbital can hold a total of 6 electrons and has 2 lobes on either the x, y, or z-axis, occurs at energy level 2
• the d-orbital can hold up to 10 electrons and occur in energy level 3
• the f-orbital occurs at energy level 4 and holds up to 14 electrons
• the 1st energy subshell only contains the s-orbital
• the 2nd energy subshell contains both the s and p-orbitals
• the 3rd energy subshell contains s, p, and d-orbitals
• the 4th subshell contains s, p, d, and f-orbitals
• electron configuration is the arrangement of electrons within orbitals
• all orbitals have to be filled before the next one can be occupied
• Dalton's atomic theory: a solid sphere. thought that atoms are the smallest particles of matter and cannot be created or destroyed. simulation showed that any photon that comes in contact with it deflects
• Thomson's atomic theory: a positively charged sphere with electrons embedded in it. in the simulation, the photons deflected when in contact with an electron
• Bohr-Rutherford atomic theory: electrons orbit the nucleus in fixed shells, in the simulation, the electron jumped up or down the shells when a photon hit it (loss and gain of energy)
• De Broglie atomic theory: wave-particle duality. demonstrates that an electron has wave-like properties and particle-like properties. the wavelengths of the electrons explain the orbits of the Bohr model. in the simulation, the electrons are shown as waves and move up or down an energy level when a photon interacts
• Schrodinger atomic theory: electrons are treated as matter waves, also known as the quantum mechanical model. an electron can only have certain energies. in the simulation, the electrons are shown as orbitals and change based on the photons interacting
• Electromagnetic spectrum (from low to high frequency):

  • radio waves
  • TV signals
  • microwaves
  • infrared waves
  • visible light
  • Ultraviolet waves
  • x-rays
  • gamma rays