​Photoelectric Effect

​When light shines on metal electrons are emitted. Sometimes they can be seen in the form of light. That light can be measured and the energy can be determined. These packets of energy are called quanta or photons.

​Quantum

Quantum ​is the minimum amount of energy lost or gained by an atom.

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​A photon is a particle carrying a quantum of energy.

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​When electrons are hit by a quantum of energy they can be promoted to a higher energy state called the excited state. The lowest energy level is called the ground state.

​Excited Electrons

​When electrons fall back to the ground state they give off energy that can be seen through a spectroscope.

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​Spectra can be used to identify the element. The frequency and energy of each photon can be calculated.

​Remember Bohr?

​Bohr said that the nucleus is surrounded by electrons, electrons are in specific orbitals, and electrons can change orbitals by absorbing to emitting photons.

​Werner Heisenberg

​Developed the Uncertainty Principle which stated that you could NOT simultaneously know the location and speed of the electron.

​Erwin Schroedinger

Developed Quantum Theory using mathematics to describe the wave properties of ​electrons. He said that electrons can behave as waves or particles, but you don't know which until they interact with matter.