Flame Test Recap WCHS Chemistry

They JUMP to higher energy levels/orbits. LOW ENERGY: red HIGH ENERGY: violet They JUMP to higher energy levels/orbits. Ground State = e- are in the LOWEST energy orbits (closest to nucleus) Excited State = e- jump to HIGHEST energy orbits (furthest from nucleus)

PHOTON When e- fall back down from excited state to ground state. Electrons need energy in order to jump up to the excited state. They will never fall down and release a photon if they don’t jump up first!

Notes #4: History of the Atom (part 4) - Quantum Mechanics WCHS Chemistry

BOHR MODEL OF THE ATOM By mid-1920, we discovered Bohr wasn’t exactly correct Model needed to be modified, but no one could do it!

Is an electron a particle or a wave? Yes! :) → It’s BOTH! THE BIG QUESTION WAS... Is an electron a particle or a wave? Yes! :) → It’s BOTH! This realization led scientists to a new model: Quantum Mechanics WHAT WE NOW KNOW!

LOUIS-VICTOR DE BROGLIE (1924) Electrons show wave-like properties. POSITIVE NUCLEUS NEGATIVE ENERGY CLOUD

ERWIN SCHRÖDINGER (1926) Developed a COMPLEX math equation to describe electron motion. Notes from Schrodinger’s lecture at Georgia tech:

CONCLUSION We have NO IDEA where an electron really is! NO ORBITS!!!

WERNER HEISENBERG (1925) Heisenberg Uncertainty Principle It is impossible to know both the position and the momentum of an electron at the same time! SPEED & DIRECTION WHERE

Think of a picture of a car.... Can you tell the exact position of the car? Which direction it’s going? How fast it’s going? If it’s moving at all?

Now think of this picture of a car... Can you tell the exact position of the car? Which direction it’s going? How fast it’s going? If it’s moving at all?

WERNER HEISENBERG (1925) Heisenberg Uncertainty Principle It is impossible to know both the position and the momentum of an electron at the same time! We have to use probability to tell us where an electron is most likely located! SPEED & DIRECTION WHERE

ORBITALS Example: If you were a betting person, where would you look for a bee? = regions of space where there is a high probability of finding an electron. Each orbital can hold 0, 1, or 2 electrons No more than 2!! Orbitals have different sizes, shapes, & names!