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Structure Of Atom

Question
CBSEENCH11005269
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Electromagnetic radiation of wavelength 242 nm is just sufficient to ionise the sodium atom. Calculate the ionisation energy of sodium in kJ mol-1. 

Solution

Energy of one photon (E) = hv
 left parenthesis straight E right parenthesis space equals space hv space equals space hc over straight lambda    ...(1)
  Here space straight lambda space equals space 242 space nm space equals space 242 space cross times space 10 to the power of negative 9 end exponent straight m semicolon straight c space equals space 3.00 space cross times space 10 to the power of 8 space ms to the power of negative 1 end exponent semicolon space space space straight h space equals space 6.626 space cross times space 10 to the power of negative 34 end exponent Js Substituting space the space values space in space eq. space left parenthesis 1 right parenthesis comma we space have space space space straight E space equals space fraction numerator left parenthesis 6.626 space cross times space 10 to the power of negative 34 end exponent Js right parenthesis space cross times space left parenthesis 3.00 space cross times 10 to the power of 8 space ms to the power of negative 1 end exponent right parenthesis over denominator 242 space cross times space 10 to the power of negative 9 end exponent space straight m end fraction space space space space space space equals 8.214 space cross times space 10 to the power of negative 19 end exponent straight J
This energy of a photon is just sufficient to ionise a sodium atom.
Thus ionisation energy of sodium
               equals space left parenthesis 8.214 space cross times space 10 to the power of negative 19 end exponent straight J right parenthesis space left parenthesis 6.022 space cross times space 10 to the power of negative 23 end exponent mol right parenthesis equals space 4.946 space cross times space 10 to the power of 5 space straight J space mol to the power of negative 1 end exponent equals space 494 space cross times space 10 cubed straight J space mol to the power of negative 1 end exponent equals space 494 space kJ space mol to the power of negative 1 end exponent

Some More Questions From Structure of Atom Chapter

What are the fundamental particles present in a neutral atom having atomic number greater than 1?

Do protons and neutrons have identical mass?

When α-particles are sent through a thin metal foil, most of them go straight through the foil. What inference do you draw from it?

What did Rutherford's experiment on scattering of particles show for the first time?

What is Plum-Pudding model of the atom?

Are neutrons present in all atoms?

Why are electrons called planetary electrons?

What are nucleons?

When is the number of protons and electron same in an atom?

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