1. Classical mechanics: how energy and forces affect the motion of macroscopic objects Ex: As the driver inputs more energy into the car, the kinetic energy of the car increases proportionately Chemical energy input into car (J) Kinetic energy (J)

2. Quantum mechanics: energy must be delivered to the electrons in specific quanta for them to be able to move to the next energy level Energy delivered to electrons (J) Energy of electrons (J) 1s 2s 2p 3s 3d 3p

3. Heisenberg’s Uncertainty Principle: it is impossible to know precisely both the velocity (or energy) and the electron’s position at the same time.

4. Alice’s Adventures in Wonderland, Chapter VI: The Cheshire Cat Gets Weirder