7.4 Summary Notes - Wave Mechanucsl Model Flashcards
Quantum or Wave Mechanical Model
Classical physics does not adequately explain the wave behaviour of atomic or sub-atomic particles due to their significant wave nature
Experimental evidence:
Moving electrons were observed to have wave properties.
Interpretation of evidence:
DeBroglie explained that electrons were circular standing waves around a nucleus. An electron can exist where there is constructive interference and cannot exist where there is destructive interference. This can be explained by Bohr’s quantized orbits.
A probability interpretation was given- the electron is found in regions of constructive interference producing a probability cloud.
In order to constructively interference what must happen?
The wavelength of the electron must fit evenly into the circumference of the orbit where the circumference is equal to the wavelength.
Page 299
The amplitude of an electron wave surrounding the nucleus of an atom may be interpreted as the ___________ of finding the electron at the location
Probability
Explain the diagrams from the question on page 301 in terms of constructive and destructive interference to explain how an energy level is “quantized”.
Destructive interference occurs between the allowed energy levels. Therefore, the wave cannot exist between orbits. This explains why electrons are allowed only certain orbits - constructive interference occurs at these certain orbits.
When an electron is treated as matter it may be interpreted as acting as a standing wave around the nucleus of an atom. What is the relationship of the radius of orbit, quantum number and DeBroglie wavelength?
2πr = nλ
Describe how the diffraction and interference of electrons in a double slit experiment may be interpreted as meaning that electrons may be thought of as waves.
Depending on the circumstances on the experiment observed a photon must be thought of as being a particle or must be treated as a wave. This is also true for electrons. When electrons are sent one at a time through double slits, an interference pattern is produced.
The Bohr model of the atom was unable to explain why only certain electrons orbits around a nucleus are allowed. Explain how the wave interpretation of an electron helps explain quantized energy levels for the electrons in orbit around a nucleus.
Only certain proportions of a wave are allowed to produce standing waves. When the electron acts as a wave surrounding a nucleus it sets up a standing wave of only certain allowed proportions.
