Quantum and Nuclear Physics (topic 7 & 12) Flashcards
The Photoelectric Effect
Refers to the emission of electrons from a metal surface as a result of the absorption of electromagnetic wave energy. Shows how light (usually thought of as a wave) can exhibit particle-like behavior.
Davisson-Germer Experiment
Electrons were scattered from atoms and these scattered electrons produced an interference pattern just like waves.
Thomas Young’s Double Slit Experiment
Shows wave behavior of light
Electron Diffraction
Shows how electrons (usually thought of as particles) can exhibit wavelike behavior (diffraction and interference).
Beta Decay
Is a process by which a nucleus emits an electron or positron. It does not showcase any wave-particle duality.
Bohr’s Model for the Hydrogen Atom
The angular momentum of the electron is quantized having values that are multiples of h/2π
Photon Energy Equation (E)
E = hf or λ = hc / E
where
E = photon energy (eV or J)
h = Planck’s constant
f = frequency (Hz)
c = speed of light
λ = wavelength (electromagnetic wave)
E is proportional to its frequency
Work Function Equation (phi)
φ = h f0
where
φ = Work function (phi)
h = Planck’s constant
f0 = threshold frequency (f0)
The De Broglie Hypothesis
Suggests that all matter exhibits wave-like properties. In particular, the momentum of a particle is related to its wavelength where the De Broglie wavelength may be deduced by the following formula:
p = h/λ -> λ = h/p -> λ = h/mv
where
p = momentum
h = Planck’s constant
λ = wavelength
m = mass
v = velocity.
Wave-Particle duality
refers to matter acting as both waves and particles.
Quantum
Refers to the smallest discrete amount of something.
Photon
Is a quantum of electromagnetic radiation (light). Exhibit wave properties under refraction or interference. Exhibit wave properties under its emission or absorption.
Angular Momentum Equation
mvr = nh / 2π
where
m = mass of electron,
v = speed of electron,
r = radius of orbit,
n = interger,
h = Planck’s constant.
Schrödinger model of the atom
P(r) = |φ|^2 multiplied by Δv
where
P(r) = probability of finding an electron in a small volume,
|φ|^2 = amplitude of wave function squared,
Δv = small volume.
Heisenberg’s Uncertainty Principle
The act of observing (making a measurement) alters the system.
Heisenberg’s Uncertainty Equation
Δx multiplied by Δp is greater than or equal to h / 4π
OR
ΔE multiplied by Δt is greater than or equal to h / 4π
where
Δx = uncertainty on position,
Δp = uncertainty on momentum,
ΔE = uncertainty on energy,
Δt = uncertainty on time,
h = Planck’s constant
Nuclear Radius Equation
R = R0 multiplied by A^1/3
where
R = nuclear radius (m),
R0 = Fermi radius constant,
A = atomic mass number
What happens when Alpha decay occurs
Add Helium 4
What happens when Beta decay occurs
Add a Beta minus (electron) + anti-electron neutrino
OR
a Beta plus (positron) + electron neutrino
Decay Equation
N = N0 multiplied by e ^ -λ t
where
N = final mass (or activity),
N0 = initial mass (or activity),
t = time elapsed,
λ = decay constant = probability of decay at a certain time.
Decays / Seconds unit
Becquerel
Half-life Equation
T1/2 = ln2/λ
where
T1/2 = half-life of exponential decay,
ln = natural log.
Element notation
Number on top of the molecule = mass # (number of nucleons) n + p
Number at the bottom of the molecule = atomic # (# of protons)
Isotopes
Same atomic number, different mass number
