Energy Levels and Photon Emission Flashcards
How do you calculate the kinetic energy carried by an electron after it has been accelerated through a potential difference of 1 volt?
E = QV
What is Excitation?
The process of an electron moving up energy levels - moving down is de-excitation
How do electrons move up energy levels?
By gaining the exact energy difference between energy levels. This can be by absorbing the energy from a photon.
What is ionisation energy?
The energy needed for an electron to go from ground state to fully removed
What are in the fluorescent tubes for Photon Emission?
Mercury vapour, coated with Phosphor inside, contains free electrons which high voltage will accelerate
How do Fluorescent Tubes work?
High-energy free electrons ionise mercury vapour - more free electrons - excite electrons in mercury atoms - move back to ground state - release Ultraviolet Photons - collide with phosphor - excite electrons - move back to ground state - release photons with visible light frequency
What are energy levels?
Orbits around a nucleus. The higher the energy levels the further from the nucleus
What are the similarities/differences collisions between electrons and atoms differ to collisions between photons and atoms?
Electrons & atoms: ionise, free more electron, excite electrons
Photons & atoms: excite electrons
What is ground state?
The lowest energy state of an atom
Describe an energy level diagram.
|______ |___.___|___\/__ | ___|__ |
|______ | __ /\__ |___.___|___\/__ |
|___.___|___|___|______ |___.___|
Ground. Excited. Excited. Ground
What is the Continuous Spectrum?
A spectrum where all wavelengths are present
What is the Emission Spectrum?
The spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule
What is the Absorption Spectrum?
A spectrum of electromagnetic radiation transmitted (absorbed) through a substance
Give an example of use of the Absorption Spectrum and how it works.
Gas cloud in space.
The light source (the sun) has a continuous spectrum. In the gas cloud, the hydrogen atoms absorbs light and emits it in random direction, making some colours weaker
