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## AP®︎/College Physics 2

### Course: AP®︎/College Physics 2>Unit 8

Lesson 2: Atoms and electrons

Using equation for Bohr model radii to draw shell model for n=1 to 3, and calculating the velocity of a ground state electron.

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Created by Jay.

## Want to join the conversation?

• Is this equation applicable only hydrogen atom?
• According to the equation - rn = n2*r1
the radius when n = 1 =1*r1
the radius when n = 2 =4*r2
the radius when n = 3 =9*r3
So distance between K and L shell = 3r1
Distance between L and M shell is 5r1
However in periodic table we learn that the distance between the shells of an atom keep on decreasing but here they are increasing.
How?
Thanks.
• Again, you can’t apply the Bohr model to other atoms.
• If the electrons have a specific range of distance from the nucleus, then that would mean that an electron could be actually anywhere inside that fixed "donut-shaped" orbit. Wouldn't it be very difficult for scientists to predict the actual position of an electron at a given time ?
• It is.
But the orbits aren't donut shaped.
And the Bohr model is not an accurate model.
• What are principal quantum numbers?
• principal quantum number is one of the four quantum numbers used to describe energy levels in the atom. it can have values n=1,2,3,4... and it determines the size of an orbital.
• FROM where did the Rydberg constant derived?
• Would the radius of the n= ∞ energy level be infinity?
(1 vote)
• does n represent the periods of the periodic table ? if not what ?
• no, it's just an integer that numbers the energy levels within the atom.
• In the video,is the r1 only for the hydrogen atom(Bohr's) or does it hold the same for all radii of the atoms
i.e is the r1 universal or does it change from element to element?
Thanks
(1 vote)
• Bohr model only applies to hydrogen and other one electron systems (eg He+, Li2+)
• Is this for hydrogen atom or for any atom?
(1 vote)
• The Bohr Model can be used for any atom, but the most common example you'll see is the Bohr Model for hydrogen.

Remember that tough the Bohr model can be useful, it also is not completely accurate in the way it represents electrons around the nucleus.

Hope this thelps!
- Convenient Colleague