Quantum Theory And Matter Flashcards
Why was quantum theory developed?
Classical models where unable to explain experimental results like black body spectrum, atomic line spectrum and photoelectric effect.
What are line spectra?
It is when atoms absorb light at characteristic frequencies. It is a coloured band with black lines.
What is the emission spectra?
Atoms emit photons at specific frequencies. It is a black band with coloured stripes.
How did Bohr’s model differ from others?
It was able to explain the existence of atomic spectra and predict positions of the hydrogen spectra lines.
How are electrons in the Bohr model treated?
They are treated as standing waves.
What do the transitions of electrons between quantised energy levels correspond to?
The lines in the atomic spectra
What is each transition a result of?
A photon being absorbed or emitted.
What must a photon have when used in a transition?
The energy the corresponds exactly to the gap between energy levels.
What are the short falls of the Bohr model?
It cannot predict spectra of atoms other than hydrogen or explain line splitting.
Why are electrons known as having wave-particle duality?
Because they also have a wave nature.
Spectra are composed of two parts…
Continuous spectra and line spectra
Spikes of increased intensify around a single wavelength are…
Emission lines
Dips in the spectrum around a single wavelength are…
Absorption lines
When is an atom happiest with its electrons?
When they are in their ground state, ie with the lowest Englert they are allowed to have.
What happens when you supply energy to an electron?
It will jump to a higher level ie an excited state.
What happen if you put a lot of energy into an electron?
It will escape and the atom will become ionised.
What does it it mean when energy levels are quantised?
It means that electrons cannot be anywhere with any amount of energy. They must be at one of the levels and must have that levels corresponding charge.
What does only allowing certain energies for an electron mean?
It means an electron can only jump down by giving off a certain energy or jump up by absorbing that same certain energy.
What does the amount of energy a photon have depend on?
It’s frequency or wavelength, as they are related.
How does an electron lose energy?
It must get rid of it in the form of light, the frequency of which is fixed by the amount of energy change.
What happen is a photon of a specific energy required by an electron comes along?
The electron will absorb it a become excited.
What gives patterns of line spectra?
As only certain energy gaps are allowed for each element, only certain wavelengths of light can be produced or absorbed.
What is the most obvious reason for line broadening?
The Doppler effect
What are the three methods of promoting an electron to a higher state?
Heat
Bombardment- other electrons that have a high potential to produce discharge.
Photon bombardment- irradiation with a specific frequency to achieve a specific transition
