Question

q1.incresing order of atomic radius na,rb,k, mg??
light of wavelength 1288 A is emitted when the hydrogen atoms drop from 5th to 3rd orbit.find the wavelength of ohoton emitted when electrons falls from 3rd to 2nd orbit????? plzz tell me

Answer 1

First you find the energy involved in the orbital transition using \[E=-2.18*10^-18 (1/2^2 - 1/3^2)\]
Which equals -3.03*10^-19 J
Then you can find the frequency by using \[E=hv\]
\[-3.03*10^-19 / 6.62*10^-34=-4.58*10^14Hz\]
Now you can find the wavelength from \[\lambda \nu=c\]
\[3.00*10^8 / 4.58*10^14\]
Which equals around 6550 angstroms

Answer 2

Also, the energy value is made positive because we are referring to the energy possessed by a photon emitted by the electron. Energy within an object is always reported as a positive number.

Answer 3

thanks @thedoctortules