chem

posted by .

What is the wavelength (in nm) of the line in the spectrum of the hydrogen atom that arises from the transition of the electron from the orbital with n =5 to the orbital with n = 2?

Note, the line corresponds to the energy of the photon that is emitted in the transition.

4.34

Find the de Broglie wavelength (in nm) associated with an electron that is moving with a velocity of 5330 km/s. The electron rest mass is 9.11 x 10-31 kg.

Note, electrons having this speed would need to be treated as waves in atoms because the wavelength is on the order of the size of atoms.

1.364e-10

• chem -

4.34 is right EXCEPT you left off the 10^-7 AND you didn't convert to nm as the problem asks.
Do it again and see if you don't get 4.34E-7 m which = 4.34E-7 x (1E9 nm/1 m)=?

For #2, 1.35E-10 is correct for meters. The problem asks for nm. You need to convert to nm.

• oops--typo -

1.3646E-10 which I would round to 1.36E-10.
Also, note that 1.364 is too many significant figures; you're allowed only 3 places.