Understanding the Atom
The nucleus of an atom is surround by electrons that occupy shells, or
orbitals of varying energy levels.
The ground state of an electron, the energy level it
normally occupies, is the state of lowest energy for that electron.|
|There is also a maximum energy that each electron can
have and still be part of its atom. Beyond that energy, the electron
is no longer bound to the nucleus of the atom and it is considered to
||When an electron temporarily occupies an energy state greater than its
ground state, it is in an excited state.
An electron can become excited if it is given extra energy, such as if it
absorbs a photon, or packet,
of light, or collides with a nearby atom or particle.
Each orbital has a specific energy associated with it. For an electron
to be boosted to an orbital with a higher energy, it must overcome the
difference in energy between the orbital it is in, and
the orbital to which is is going. This means that it must absorb a photon
that contains precisely that amount of energy, or take exactly that amount
of energy from another particle in a collision.
Electrons do not stay in excited states for very long - they soon
return to their ground states, emitting a photon with the same
energy as the one that was absorbed. |
Transitions among the various orbitals are unique for each element because the
energy levels are uniquely determined by the protons and neutrons in the
the electrons of a certain atom return to lower orbitals
from excited states, the photons they emit have energies that are
characteristic of that kind of atom. This gives each
element a unique fingerprint, making it possible to identify the elements
present in a container of gas, or even a star.