Question

we have a collection of hydrogen atims in the ground state. They are bombarded sith photons of energy 12.2 MeV. what are the energies of the photons that can be emitted by thr excited hydrogen atoms

b) why do fission and fusion release much more energy than chemical burning or a chemical explosion

Answer 1

We know that the ground state energy of hydrogen atoms is E1= -13.6 eV. After absorbing photons hydrogen atoms get excited and their corresponding can be obtained as

The energy of the excited state is

z=1 for hydrogen atom. We shall be applying the conservation of energy.

The energy of the emitted photon will be

Initally they were in the ground state and having energy -13.6 eV and absorbs 12.2 MeV so their final energy becomes

Here, E represents the energy of emitted photon. Using Eq.(2)

(b) Fusion and fission are nuclear processes. They involve high energies and deals with gamma radiations and photons which are very high in energy like in MeV. Additionally, we know that the nuclear forces are the strongest so to overcome those forces who are binding the nucleus much more energy is needed than the usual breaking of the bonds in atoms. On the other hand, the chemical reactions take place at a very low energy usually of the few orders of joules or can be interpreted as in milli electron volts. In chemical reactions, one usually deals with the electrons in the outer orbit unlikely the nucleus as in the previous case. So the energies released in radioactive processes or nuclear processes like fission and fusion is much more than the energy released in chemical processes.