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Chapter 6.1-6.3

- Electronic Structure of Atoms

Electromagnetic Radiation

- Radio MW IR Visible UV

X-ray ?-ray - Wave
- R-O-Y-G-B-I-V
- Wavelength (?) decreases
- Frequency (?) increases
- Velocity of radiation (c) 3.00 x 108 m/s
- Note Velocity of radiation is fixed.

Electromagnetic Radiation

- Frequency (?) wavelengths/s

c ? ?

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Plancks Theory

- Energy is emitted or absorbed in whole-number

multiples of h? - h 6.63 x 10-34 Js, 1 J 1 kg m2/s2
- ? Frequency of radiation
- Allowed 1 h?, 2 h?, 3 h?, etc.
- NOT allowed 1.5 h?, 2.3 h?, 3.3 h?, etc.
- Quantized energy!
- Not continuous!

Photoelectric Effect

- Energy of ejected electrons depends upon

frequency of radiation. - Einstein explains by assuming radiation to be

made up of photons (tiny particles). - Ephoton h?
- h 6.63 x 10-34 Js
- ? Frequency
- Problem 10,23 Pg. 252-253
- Hint c ? ?

Predict outcome

- Note A.) is glued
- onto the surface.
- Binding energy (BE)
- Will A.) be ejected in I or II?
- No (I), yes (II)
- If ejected, how much energy will it carry?

(assume complete energy transfer) - 2 J (in II) 10 J 8 J

Predict outcome

- In II, the energy of ejected A.) is
- Ekinetic 10 J 8 J 2 J
- Energy of BE of A.)
- striking B.)

Ekinetic Ephoton BE Or h? -

BE (kinetic energy of ejected e-)

- Problem 6.26, Pg. 253
- Continuous Spectrum ? R-O-Y-G-B-I-V
- Line Spectrum ? Spectrum containing specific

wavelengths.

Bohrs Model

- Explains line spectrum
- Ei (initial energy) ? 6 (level 2)
- Ef (final energy) ? 10 (level 3)
- Change in energy
- (absorbed by e-)
- ? E 10 6 Ef Ei 4
- Absorbed or given off?
- Absorbed

Bohrs Model

- What will happen if e- jumps from level 3 ? 2?

Ef 6, Ei 10 - ? E Ef Ei 6 10
- -4, abs or given off?
- Given off

Bohrs Ei -RH (1/ni2) n 1,2,3,

etc. Ef -RH (1/nf2) RH Rydbergs

constant 2.18 x 1018 J

Bohrs Model

- ? E Ef Ei
- ? E RH (1/ni2 - 1/nf2)
- Use this expression in solving problems in which

e- jumps from level ni ? nf. - Problems 33, 39 Pg. 254

h? ? E RH (1/ni2 - 1/nf2) hc/?