Need Help Understanding Bohr Model Equations

[jcmartinez]

Bohr incorporates Plancks's quantum theory into his model, placing conditions on the value of the angular momentum.

angular momentum = nh/2pi

n=principal quantum number h= Planck's constant

since its giving me the angular momentum, is it actually giving me a number that corresponds to an orbital. s,p,d, or f?

Bohr then equated the allowed values of the angular momentum to the energy of the e-. He obtained the folowing equation:

E=-R(little h)/n^2

R(little h) is Rydeberg constant for hydrogen right. N= principal quantum #

the value of zero was assigned to the state at which the e- and proton were separated completely. this makes sense since the bigger the n value is= the further orbit it is away from the proton= the closer the E gets to zero.

now i do not quite understand two things. Why the negative sign?? and E denotes the energy of the e- right. what exactly does this energy do or mean for the electron?

using this formula E=13.6-(13.6/n^2)
E = energy
n= energy level.
using that formula Bohr predicted the energy levels for each of the allowable orbits in the Hydrogen atom.

now i would like to understand why 13.6 is used?
and what does this information actually tell us.

please help as best you can. i have tried reading things up on Wikipedia but that does not help me much.

 

[SpectraCat]

Bohr incorporates Plancks's quantum theory into his model, placing conditions on the value of the angular momentum.

angular momentum = nh/2pi

n=principal quantum number h= Planck's constant

since its giving me the angular momentum, is it actually giving me a number that corresponds to an orbital. s,p,d, or f?

Bohr then equated the allowed values of the angular momentum to the energy of the e-. He obtained the folowing equation:

E=-R(little h)/n^2

R(little h) is Rydeberg constant for hydrogen right. N= principal quantum #

the value of zero was assigned to the state at which the e- and proton were separated completely. this makes sense since the bigger the n value is= the further orbit it is away from the proton= the closer the E gets to zero.

now i do not quite understand two things. Why the negative sign?? and E denotes the energy of the e- right. what exactly does this energy do or mean for the electron?

using this formula E=13.6-(13.6/n^2)
E = energy
n= energy level.
using that formula Bohr predicted the energy levels for each of the allowable orbits in the Hydrogen atom.

now i would like to understand why 13.6 is used?
and what does this information actually tell us.

please help as best you can. i have tried reading things up on Wikipedia but that does not help me much.

The value of 13.6 is just reflective of a choice of units. The particular choice in this case is known as an electron-volt, which is defined as the amount of kinetic energy gained by an electron when it is accelerated through a potential of one volt. You can convert it into whatever energy units you want .. in joules the 13.6 eV amounts to about 2.18x10^-18 J. This energy corresponds to the ground state energy of the H-atom .. the highest possible amount of energy by which an electron can be bound to an H-atom nucleus. This quantity is also called the ionization energy of the atom, because (by conservation of energy) it is also the amount of energy that you need to add to the atom in order to remove the electron.

 

[epenguin]

Bohr incorporates Plancks's quantum theory into his model, placing conditions on the value of the angular momentum.

angular momentum = nh/2pi

n=principal quantum number h= Planck's constant

since its giving me the angular momentum, is it actually giving me a number that corresponds to an orbital. s,p,d, or f?

I think the Bohr model as you have expounded it corresponds only to the
s orbitals. The others were dealt with by Sommerfeld who made their orbitals elliptical. They did not work completely but their predictions were tantalisingly near.