Quantum Phenomenon Flashcards
(32 cards)
What is an electron volt (eV)?
The kinetic energy gained by an electron after experiencing an accelerating potential of one volt
1 eV = 1.6 x 10^-19 Joules
What does the term ‘quantum’ refer to in quantum mechanics?
The concept that energy at the smallest scales is discrete rather than continuous
What is the lowest possible energy state of an electron called?
Ground state
What happens when an orbital electron receives energy?
It moves into an excited state
What is emitted when orbital electrons de-excite?
A photon
What are the two mechanisms for an orbital electron to become excited?
Excitation by collision and excitation by absorption
What condition must be met for excitation by absorption?
The energy of the photon must equal the change in energy between the two electric energy levels
What is ionization energy?
The amount of energy required to remove an electron (in the ground state) from an atom
What does De Broglie’s hypothesis propose?
That particles exhibit wave-like properties
What experimental evidence supports the wave-like nature of particles?
Electron diffraction
True or False: The energy levels of electrons get farther apart as they increase.
False
What is the significance of the photoelectric effect in quantum mechanics?
It demonstrates the particle-like nature of waves
What is the mass of an alpha particle in terms of atomic mass units?
4 times the atomic mass unit
What are characteristic photons?
Photons produced by electrons of an element when they de-excite
Each element has its own fingerprint of different characteristic photons.
What is an emission spectrum?
A spectrum produced by separating the characteristic photons of an element
This spectrum represents the unique energy levels of an element.
How do fluorescent tubes work?
A current is passed through mercury vapour, causing it to emit UV photons
The inside of the tube is coated with phosphor that converts UV photons to visible light.
What is the role of phosphor in fluorescent tubes?
It absorbs UV photons and re-radiates energy in the visible spectrum
This makes the emitted light usable for human vision.
What did Max Planck introduce in 1900?
The notion that radiation is quantized
This was to derive the black body radiation spectrum.
What significant idea did Albert Einstein present in 1905?
He explained the photoelectric effect using Planck’s quantization concept
This led to the acceptance of the quantum nature of radiation.
What did Niels Bohr achieve in 1913?
He predicted the line spectrum of the hydrogen atom using quantization of radiation
This was based on the quantization of angular momentum of electrons.
What experimental confirmation was achieved in 1927?
Confirmation of matter waves through electron diffraction
This was demonstrated by Clinton Davisson and Germer, and G.P. Thomson.
Each element on the periodic table has a unique set of …
Energy levels
These energy levels correspond to the number of protons in the nucleus.
What occurs when light of a certain frequency is shone onto a sheet of metal?
The photoelectric emission
It involves electrons absorbing energy from light until they escape the metal.
How does the photoelectric effect demonstrate the particle-like nature of electromagnetic radiation?
Some light sources did not produce a current regardless of intensity
Wave theory suggested that energy would eventually cause electron emission.
