Question

Does the whole Balmer series fall in the visible region? Write and example for n initial use 7 to demonstrate.

Answer 1

Not really..

Balmer series will only fall in to visible light in

n = 2,3,4,5,6

for n = 7, there is UV region

proof:

Apply Rydberg Formula

E = R*(1/nf^2 – 1/ni ^2)

R = -2.178*10^-18 J

Nf = final stage/level

Ni = initial stage/level

E = Energy per unit (i.e. J/photon)

E = (-2.178*10^-18)*(1/7^2 – 1/2 ^2)

E = 5.0005*10^-19

For the wavelength:

WL = h c / E

h = Planck Constant = 6.626*10^-34 J s

c = speed of particle (i.e. light) = 3*10^8 m/s

E = energy per particle J/photon

WL = (6.626*10^-34)(3*10^8)/(5.0005*10^-19) =

WL = 3.9752*10^-7 m

to nanometers:

WL = (3.9752*10^-7)(10^9) = 397.52 nm

this is less than 400 nm visible for human eye, this is UV region