Answer:
Energy levels : It refers to the shells of definite energy in which electron revolves around the nucleus .
Step-by-step explanation:
As we know, that atom consist of small dense mass that is nucleus and around it the shells of definite energy are present .
We also know ,atom consist of sub atomic particles that is :
- In shells the electrons are present and are not stationary (they are revolving ).
- The electron never absorbs or releases energy by itself .The electron in shells have definite energy that is the reason the shells are referred as energy levels .
- But, when we supply energy to electron which is more than the energy of the shell then it gets excited to higher energy level (depending upon magnitude of energy supplied ).
- The higher energy level is regarded as excited state .
- The excited states are always unstable .
- So, electron revolves there for short span of time but ultimately it returns to its own shell and by doing so it release the energy absorbed by it .
- The energy released is actually a difference in the energy of ground state (original state ) and energy of excited state .
- ΔE=E₂-E₁