Light is a stream of particles. Particles are called photons, and have a zero rest mass, carrying a quantum of energy.
Model of the hydrogen atom. Electron orbits nucleus in orbits, but not in between them. Lowest energy is closest to nucleus, highest energy is farthest from nucleus.
Electrons are wavelike and particle like. Orbitals can hold up to 2 electrons. Different types of orbitals have different shapes.
Uncertainty Principle, quanta can not be accurately measured because forces are always acting upon them. Even photons can increase the velocity.
An electron occupies the lowest energy orbital that can receive it.
No two electrons in the same atom can have the same set of four quantum.
Orbitals of equal energy are each occupied by one electron before any orbital is occupied.