physics trip: monday 8 th april need payment and permission slips back by friday reminder: internal...
Post on 14-Jan-2016
215 Views
Preview:
TRANSCRIPT
• Physics trip: Monday 8th April
• Need payment and permission slips back by Friday
• Reminder: internal – last week of term
• Tasks to complete:
homework and old exam questions (nuclear and photo-electric effect)
• We have one more topic to cover before the internal: atomic spectra
homework set and old exam questions for this also
Student feedback:
H/W books
Textbook work
Do now / starter activities
Revision booklets
Worksheets
Playing with the diffraction grating and lasers
Doppler applications (speed radar, expansion of the universe)
Estimating and processing uncertainties
Experiment 1: measuring standing waves with ticker timers
Experiment 2: measuring the wavelength of a laser using a diffraction grating
Video clips
Phet animations
Ruben tube demo
Mini tests
Do the sticker timeline
Notes on Bohr’s model
photons of white light(all frequencies)
shone through a sample of gas
most frequencies pass straight through
but some are absorbed
and re-emitted (in random directions)
Absorption spectrum: dark lines indicate the “missing” frequencies (the absorbed photons)
Where would you place the spectrometer to detect the emitted photons? (the emission spectrum)
The Hydrogen SpectrumThe Hydrogen Spectrum
1 2 3 4 5
Lyman Series S=1 (UV)
Balmer Series S=2 (visible)
Paschen Series S=3 (IR)Bracket Series S=4 (IR)
Pfund Series S=5 (IR)
Nucleus
Shell no. / Energy level
The Hydrogen SpectrumThe Hydrogen Spectrum
The wavelengths of the emitted photons are The wavelengths of the emitted photons are given by:given by:
R=Rydberg’s Constant=1.097x10R=Rydberg’s Constant=1.097x1077 m m-1-1
S=Series no. (the shell jumped into)S=Series no. (the shell jumped into)L=Line no. (the shell jumped from)L=Line no. (the shell jumped from)
22
111
LSR
Bohr’s Model of the AtomBohr’s Model of the Atom
The energy levels in the Hydrogen atom are The energy levels in the Hydrogen atom are given by :given by :
h=Plancks constant = 6.63x10h=Plancks constant = 6.63x10-34-34 Js Js c=speed of light = 3x10c=speed of light = 3x108 8 msms-1-1
R=Rydbergs constant = 1.097x10R=Rydbergs constant = 1.097x1077 m m-1-1
n=energy level = 1,2,3,4…… (quantum number)n=energy level = 1,2,3,4…… (quantum number)
2n
hcREn
Bohr’s Model of the AtomBohr’s Model of the Atom
-1
-2
Energy
(x10-18J)
0
n=1
n=2
n=3n=4
n=∞
181
2
7834
1
1018.2
1
10097.11031063.6
E
E
QuestionsQuestions
1)1)Calculate the wavelength and frequency of the Calculate the wavelength and frequency of the first line in the Balmer seriesfirst line in the Balmer series
2)2)An electron in a hydrogen atom falls from the An electron in a hydrogen atom falls from the third to the second energy levelthird to the second energy level
a) How much energy does the electron lose?a) How much energy does the electron lose?
b) What is the energy of the photon emitted?b) What is the energy of the photon emitted?
c) What is the frequency of the emitted photon?c) What is the frequency of the emitted photon?
textbook p182
textbook p187
top related