Atomic Theory Part 3 Quantum Mechanical Model

Louis de Broglie

originated the idea that the electron, previously considered just a particle, has wave properties.

Werner Heisenberg

it is impossible to simultaneously know the exact position and speed of an electron (Heisenberg’s Uncertainty Principle).

Erwin Schrödinger: Electron Behaviour

• electrons behaved like light (a particle with wave properties).

• electrons do not orbit atoms, but are found in spaces around the atom called orbitals.

• The exact location of an electron cannot be determined;

  however, there is a high probability of finding an electron

  in an orbital.

Orbits are ___ as a Bohr orbit

Not the same

Orbital vs orbit

Whats an orbital

• the region around the nucleus where an electron

  has a high probability of being found.

• also known as an electron probability density, which is a 3-dimensional plot. This plot is the solution to a wave function (equation), which is a mathematical description of an orbital.

Orbitals still correspond to

energy levels (Bohr was correct about this); that is electrons can exist in an energy level, but not in between them.

Orbitals and Electrons

• each orbital orientation can hold up to 2 electrons

• electrons in the same orbital will have opposite spins cw ccw

• as you increase the distance from the nucleus (ie: higher

energy levels), there is room for more orbitals

Orbitals and Energy Levels Chart

What do energy level diagrams represent

• the position of the electrons in an atom

• Simplifies so we can see how the electrons are arranged

• Understanding electron arrangement will help you understand how tthe periodic table is arranged and the trends that exist

Energy level diagrams rules

1. Electrons go in the lowest energy levels first

2. Each orbital can have a maximum of two electrons (it is possible for an orbital to have one electron, or none).

3. Electrons in a sublevel will not pair up until all orbitals have one electron each.