A Basic Understanding of Quantum Theory
When most people think of atoms they picture the common picture of electrons spinning around a nucleus. In spite of the popularity of the image, according to classic Newtonian physics these atoms would become unstable and collapse. Thus scientists came up with a new theory that describes physics on an atomic and subatomic level. This new theory is called quantum theory and the new kind of physics is known as quantum physics.
One thing that is true about the common picture of atoms is that electrons circle around the nucleus. They each have a certain orbit that they stay in. When an electron is affected by a packet of energy called a quanta, it changes orbit and emits or absorbs light particles.
In 1900 a scientist named Max Planck made an assumption that energy was composed and found in tiny packets called quanta. This was the original quantum theory.
In 1905 Einstein said that energy changes occur when electrons change orbits. This came about while he was studying the photoelectric effect and he combined this with Planck's theory. The only way an electron can change orbit is if it is affected by quanta. It's orbit is then quantized and it changes to a different orbit.
Quanta comes in forms of energy. For example, you could have a light quanta or a heat quanta. These float around and affect atoms. In 1927 a scientist named Werner Heisenberg developed the uncertainty principle. This stated that for these particles you could never know the position or the momentum of any of them. This is in contrast to Newtonian physics which stated you could predict you could predict the path and momentum of a particle based on it's current conditions.
When a electron changes to a higher orbit...