Explain the experiment that Balmer series is based off
A high voltage electrical discharge is passed through H_2 (g) ; emitted light passed through a prism,(narrow lines/slits); The lines shows different wavelength
1 of 20
State the equation for the Balmer seies
1/lambda = constant (1/2^2 -1/n^2) ] where the constant: 1.097*10^7 m^-1
2 of 20
State the Rydberg equation
1/lambda = R(1/m^2 -1/n^2 ) ] where m<n and m and n correspond to principal quantum numbers
3 of 20
State the Lyman series
1/lambda = R(1/1^2 -1/n^2)
4 of 20
Why does line spectra show that the Rutherford model is incorrect?
if true then atoms would emit continuous spectra and they would be unstable (electrons would spiral and collapse in to the nucleus)
5 of 20
What are 'orbits' as states by Bohr?(one of his postulates)
Electrons have orbits which are quantized ; that is to say that orbits have definite energy levels
6 of 20
What does mechanical stability have to do with atoms?
Coulomb attraction obeys the law of classic mechanics; thus coulomb attraction =centripetal force
7 of 20
Derive an equation for the speed of an electron in an orbit
v^2 = e^2 /4pi*epsilon_0 *m_e *r (derived from the equations of centripetal force and coulombs force--> equating them)
8 of 20
What is the angular momentum of electrons as stated by Bohr?( another postulate)
Angular momentum is quantisised/ restricted to integer multiples of h/2pi; it keeps electrons in orbit
9 of 20
State the equation of angular momentum of the electrons
L= m_e *rv=nh/2pi
10 of 20
State the equation of the radii of an orbit (directly from coulomb and centripetal equations)
r= (epsilon_0 *n^2*h^2)/(pi*e^2*m_e)
11 of 20
Derive the simplified equation for the radii of orbits
r_n = 0.529 *n^2 (Angstrom)
12 of 20
State another equation for the velocity of electrons (using equations of v and r above)
v= e^2/2*epsilon_0 *n*h
13 of 20
Bohr also gives equations for the energy of the electrons in nth orbit. State this
E_n = -13.6/n^2 (eV)
14 of 20
What happens to E as n tends to infinity and what does this mean?
E tends to zero which means that the -ve sign show that energy is being released.
15 of 20
Give Bohr's third postulate
An electron is allowed to make transition from one orbit to another and to do so it must either absorb or emit a photon
16 of 20
State the equations that are related to Bohr's third postulate
r_n = 0.529n^2 /Z Angstroms ( where Z is the # of protons )
19 of 20
Name some limitations of the Bohr's model
Only works for single electron system; there is no proof for the first two postulates; cannot explain relative spectra intensity which highlight that some transitions are more favoured than others
20 of 20
Other cards in this set
Card 2
Front
State the equation for the Balmer seies
Back
1/lambda = constant (1/2^2 -1/n^2) ] where the constant: 1.097*10^7 m^-1
Card 3
Front
State the Rydberg equation
Back
Card 4
Front
State the Lyman series
Back
Card 5
Front
Why does line spectra show that the Rutherford model is incorrect?
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