SCH4U1
The Wave (Quantum) Mechanical Model
Problems with Bohr’s Model:
Bohr visualised the e- as a particle by which its exact location and momentum could
be determined. Actually, the e- is so small that it has both particle and wave properties so
we cannot specify exact orbits. Another problem is when an electron changes energy levels
during the emission of atomic spectra.
An electron can never be “in-between” energy levels so it is clear that this model has
limitations and a new model needs to be generated.
The study of quantum mechanics is a branch of mathematics which studies the
properties of electrons. In this class we will use the results of the calculations. (You can
do them later in 3rd and 4th year university)
Wave Mechanics tells us there are certain regions in space around the nucleus where the eis most likely to be at any given time. Wave mechanics is based on probability.
These regions are called ORBITALS, indicating the e- has a high probability of being
in that area.
Electron
density
Distance from nucleus
The electron is not found at the nucleus but is more likely to be located closer to the
nucleus.