The electron energy in hydrogen atom is | Class 11 Chemistry Chapter Structure of Atom, Structure of Atom NCERT Solutions

Question:

The electron energy in hydrogen atom is given by En = (–2.18 × 10–18)/n2 J. Calculate the energy required to remove an electron completely from the n = 2 orbit. What is the longest wavelength of light in cm that can be used to cause this transition?

Answer:

The expression for the energy of hydrogen of electron is

En = -2π2me4Z2/n2h2

Where m= mass of electrons

Z=atomic mass of atom

e = charge of electron

h = planck’s constant

When n = 1 then En = - (2.18X10-18 ) (GIVEN)

When n = 2 then En= - (2.18X10-18 )/4 = 0.5465X10-18 J

 

Therefore the energy required for ionization from n = 2 is 5.45 x 10-19 J

Now wavelength of light needed

= E=hv = hc

Or

λ = [{(6.62x10-24)(3x108)} / 5.45] x 10-19 = 3647


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Comments

  • Krishna kumar
  • 2019-08-24 00:01:52

5.45*10to the -19


  • Shivam
  • 2019-07-21 12:00:36

All wrong value of plank constant is 6626.10power_34


  • Kalyani
  • 2019-05-24 17:02:21

the answer is also wrong with no specified unit


  • Mitali
  • 2019-05-14 13:21:24

The value of planck's constant is wrong.


  • Anonymous
  • 2018-05-24 02:15:33

Really helpful 🙄😄


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 11 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 19: The electron energy in hydrogen atom is given by En = (–2.18 × 10–18)/n2 J. Calcul....