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Ex) How much energy is absorbed when an electron in hydrogen moves from the energy levels n = 2 to n = 5?

Subtract the absolute values to find the energy needed to be absorbed

Answer

3.4 eV - .54 eV = 2.86 eV

Ex) How much energy is needed for an electron in the n = 1 energy level to move to the n = 2 energy level?

n = 1      -13.6 eV
 n = 2       -3.40 eV

Throw out the negative signs and subtract

= 13.6 eV - 3.4 eV

= 10.2 eV Absorbed

 Frequency of photon absorbed

E = hf

E = 10.2 eV

Convert eV to Joules

page 1 Reference

1 eV = 1.6 x 10^-19 J

E = 10.2 eV x 1.6 x 10^-19 J

= 1.6 x 10^-18 Joules

f = E/h

f = 1.6 x 10^-18 Joules/6.63 x 10^-34 Js

Ex) Which energy level transition in MERCURY will produce a photon emission of .22 ev?

Answer: c to b transition
 

5) Ionization Energy - energy needed to remove an electron from an atom.

Ionization Energy - greater than or equal to energy at that level.

Ionization Energy of Hydrogen

n = 1

13.6 eV or greater

n = 2

3.4 eV or greater

n = 3

1.51 eV or greater

Ex) A photon having an energy of 15.5 electron volts is incident upon a hydrogen atom in the ground state. The photon may be absorbed by the atom and

a) ionize the atom

b) excite the atom to n = 3

c) excite the atom to n = 2   

d) excite the atom to n = 4

a) ionize the atom