LECTURE 3 โ Chapters 5

Slide NumberNotes ๎

11 EX.

-binding energy = 7.21 x 10^-19 J

-E of photon > or = 7.21 x 10^-19 J

-Longest wavelength = 6.63x10^-34 Js (3.00x10^8 m/s) / 7.21 x

10 ^-19 J = 2.76 x 10^-7 m = 276 nm

-Will light with 290 nm eject electrons? NO

-This is because increasing wavelength = decreasing frequency

-276nm is the longest wavelength that will eject electrons

-below this threshold, no electrons ejected

-increasing wavelength is decreasing energy

-energy of photon = binding energy + kinetic energy of electron

= 7.21x10^-19 J + 2.5 x 10^-19J = 9.7x10^-19J

-v = E/h = 9.7x10^-19 J / 6.676x10^-34Js = 1.5x10^15/s

-wavelength = c/v = 3.00x10^8 m/s / 1.5 x 10^15/s = =210nm

13 -monochromatic = one colour

-energy needed to eject energy from Zn > than for Na therefore

A wrong

-same number of electrons ejected from both metals because

same intensity of light shone for both therefore B and C wrong

-zinc has a higher threshold frequency, therefore there is less

kinetic energy therefore D is wrong

-Ans: E

14 -electron can only be at certain levels of the atom

-like stairs: a fixed number of positions

-unlike a ramp: an electron cannot be anywhere, cannot fall from

just any position

16 -de Broglie suggested that electrons may behave as waves

-important for small objects (ie. electrons) because of the inverse

relationship such that the smaller the mass, the longer the

wavelength

17 -uncertainty significant for tiny masses

-electronic structure BEFORE 1900: light as waves, continuous,

spread out, mass-less; matter as discrete particles with mass and

position

-experiments (ie. blackbody radiation, photoelectric effect),

however, put forward the wave-particle duality (waves behaving

as particles and particles behaving as waves)

-instead of trying to pinpoint the exact location of electron, focus

instead on probability of finding the electron

18 - the many solutions refer to the different locations of the electron

19 - Schrodingerโs equation gives orbitals and energy

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