All Flashcards
Differentiate between the Dalton and Thomson atomic models.
Dalton: Atoms are indivisible spheres. | Thomson: Atoms are a positive 'pudding' with embedded electrons.
Compare and contrast classical physics and quantum mechanics regarding blackbody radiation.
Classical Physics: Predicted infinite energy emission at high frequencies (UV catastrophe). | Quantum Mechanics: Energy is emitted in discrete packets (quanta), resolving the catastrophe.
Explain the difference between low frequency and high frequency light in the photoelectric effect.
Low frequency light: Metal absorbs the light, no electrons are ejected. | High frequency light: Electrons are ejected. The kinetic energy of the ejected electrons increases with the frequency of the light.
Describe the photoelectric effect.
Light strikes a metal surface. If the frequency is above the threshold frequency, electrons are ejected. The kinetic energy of ejected electrons increases with the light's frequency.
Outline Rutherford's gold foil experiment.
Alpha particles were directed at gold foil. Most passed through, but some deflected. This indicated a small, dense, positive nucleus.
Define 'quantum'.
A discrete packet of energy.
What is 'Planck's constant'?
The constant (h) relating energy and frequency, approximately 6.626 x 10^-34 Js.
Define 'photon'.
A particle of light with energy proportional to its frequency.
What is 'threshold frequency'?
The minimum frequency of light required to eject electrons from a metal surface in the photoelectric effect.
Define 'work function'.
The minimum energy required to remove an electron from a solid, also known as binding energy.
What is the 'ultraviolet catastrophe'?
The prediction by classical physics that a blackbody would emit infinite energy at high frequencies.