Quantum Physics Flashcards
What is the particle model of matter?
Objects are hard, have mass, and move according to Newtonian mechanics.
What is the wave model of matter?
Waves have no mass or charge and exhibit diffraction and interference.
What is the photoelectric effect?
When electromagnetic radiation of sufficiently high frequency falls on a metal surface, electrons are emitted.
What are the emitted electrons in the photoelectric effect called?
Photoelectrons.
What is photoelectric current?
The current due to the emission of photoelectrons
What is the 1st law of photoelectric emission?
The number of photoelectrons emitted per second is directly proportional to the intensity of incident radiation
What is the 2nd law of photoelectric emission?
The maximum kinetic energy of photoelectrons is directly proportional to the frequency of the incident radiation but independent of its intensity.
What is the 3rd law of photoelectric emission?
Each metal has a threshold frequency below which photoelectric emission does not occur.
What is threshold frequency?
The minimum frequency required to release electrons from the surface of a metal.
What is a photon?
A quantum (particle) of electromagnetic radiation.
What is the equation for the energy of a photon?
E=hf, where ℎ = 6.63 × 10 ^ -3 Js (Planck’s constant).
What is work function (Φ)?
The minimum energy required for an electron to escape a metal surface
What is Einstein’s photoelectric equation?
hf=ϕ 0 + E max, where 𝜙 0 is the work function and 𝐸 max is the maximum kinetic energy of the emitted electron
How is the energy of an absorbed photon distributed?
Some energy releases the electron from the metal, and the remaining energy contributes to its kinetic energy
What wave-like behavior does electromagnetic radiation show?
Diffraction and interference
What particle-like behavior does electromagnetic radiation show?.
The photoelectric effect.
What conclusion does wave-particle duality lead to?
Electromagnetic radiation has both wave and particle properties.
What was de Broglie’s hypothesis?
Particles should exhibit wave-like behavior.
What is the de Broglie wavelength equation?
λ= h/p = h/mv, where ℎ is Planck’s constant, 𝑚 is mass, and 𝑣 is velocity.
What happens when a beam of electrons passes through a thin carbon foil?
A diffraction pattern is observed, confirming the wave-like nature of electrons.
What is the ground state of an atom?
The lowest energy state of an atom.
What happens when an atom absorbs energy?
It moves to an excited state.
What happens when an atom releases energy?
It emits electromagnetic radiation and returns to the ground state.
What equation describes the energy difference between two levels in an atom?
hf =E 2 − E 1, where 𝐸 2 is the higher energy level and 𝐸 1 is the lower energy level.
Why are the energy levels of an atom quantized?
Electrons can only absorb or emit specific discrete energy values.
What is an emission line spectrum?
The composition of light emitted by a hot gas, showing discrete wavelengths.
What is an absorption line spectrum?
The pattern of wavelengths absorbed by electrons when white light passes through a cool gas.
Why do elements have unique emission and absorption spectra?
Because their electron energy levels are unique and quantized.
