Introduction to Quantum Theory

  Quantum theory is the basis of physics that explains the nature and behavior of matter and energy on the atomic and subatomic level.(That just means we study atoms very closely and how they behave.)  The nature and behavior of matter and energy at that level is sometimes referred to as quantum physics and quantum mechanics.

Quantum theory states that there are only certain allowed energy states for an electron and that these are quantized. Further, it tells us that no two electrons, in the same system, can occupy the same energy state, and that all the energy states are filled from the lowest levels to the highest levels.