Quantum Mechanics

Three key elements of Quantum Mechanics

-The universe is fundamentally statistical in nature

-Energy levels and states are discrete, not continuous

-Any object can be described as a particle or as a wave.

Electron volt (eV)

The amount of energy needed to move one electron through one volt of potential and is the unit of energy most commonly used in modern physics.

Ground state

The lowest energy state for an electron in an atom, corresponding to the n=1 state

Ionization State

The energy needed to strip an electron from an atom, corresponding to the state n=infinity

After this, the atom becomes a positively charged ion.

T/F The energy of a photon depends only on its frequency.

True

T/F Electrons orbit the nucleus like planets around the sun.

false

T/F Planck’s constant is a very large number, so quantum effects are obvious in everyday life.

False

T/F The photoelectric effect depends on the intensity of light only.

false

T/F The universe at the quantum level is deterministic, just like Newtonian mechanics.

false

Which formula gives the wavelength of a particle?
A) E=hfE=hf
B) λ=h/pλ=h/p
C) f=c/λf=c/λ
D) ΔE=Em−EnΔE=Em​−En​

B) λ=h/pλ=h/p

An electron transitions from n = 1 to n = 2 in hydrogen. The energy required is:
A) 13.6 eV
B) 10.2 eV
C) 12.1 eV
D) 1.6 eV

B) 10.2 eV

The uncertainty principle tells us that:
A) We cannot measure energy at all
B) Δx⋅Δp≥hΔx⋅Δp≥h
C) Electrons always have fixed positions
D) Light behaves only as a wave

B) Δx⋅Δp≥hΔx⋅Δp≥h

Compton scattering shows that:
A) Electrons move in fixed orbits
B) Light has momentum
C) Energy levels are continuous
D) Photons do not interact with matter

B) Light has momentum

Which of these is NOT a result of energy quantization?
A) Atomic spectra
B) Photoelectric effect
C) Blackbody radiation
D) Classical motion of a baseball

D) Classical motion of a baseball

T/F Quantum mechanics is completely unnecessary to describe how things function.

FALSE its necessary to describe how atoms function

T/F The momentum and position of an electron in an atom can be exactly detmermined

FALSE

You can’t know the exact position and exact momentum of an electron at the same time.

Because electrons don’t act like tiny little balls — they act like waves.
When you try to measure their position, you disturb their momentum.
When you try to measure their momentum, you lose track of their exact position.