[00:00]	Atomic Structure
[00:22]	What is an Atom?
[17:40]	The Optical Spectrum
[18:17]	The Spectrum of Clothes
[19:15]	Atomic Transitions
[20:28]	The Atom as a Well
[21:34]	The Solar System as a Smooth Mountain
[22:24]	The Atom as a Set of Discrete Steps
[23:36]	Atomic Transitions (reprise)
[24:28]	Multiple Energy Levels
[25:54]	Energy Levels
[27:56]	Continuum Spectrum
[28:13]	Absorption Spectrum
[30:41]	Atomic Transitions (reprise)
[37:09]	Absorption and Emission from atoms
[45:40]	Quantum Mechanics

Learning Objectives

1. Understand the internal structure of the atom.
   • Place heavy protons and neutrons in the nucleus, light electrons in a cloud surrounding it.
   • Connect atomic number (number of protons) to element (hydrogen, helium, lithium, etc.).
   • See how experimentation improved our visualization of the atom.
   • Become comfortable with the notation used to describe atomic species (such as ¹²C₆ for carbon).

2. Comprehend the key features of the Bohr model.
   • Electrons can exist only at set, spaced orbitals (energy levels) within an atom.
   • An atom must absorb energy to shift an electron to a higher energy level.
   • An atom must emit energy to shift an electron to a lower level.
   • The pattern of absorption and emission from an atom is like a fingerprint, and reveals which element it is.

3. Relate the energy levels within an atom, and their population with electrons, to the pattern of emission and absorption seen in spectra when observing an element in space.

4. Embrace the key findings of quantum mechanics.
   • Energy is quantized into packets, and cannot be divided into arbitrarily small amounts.
   • The act of observing alters the reality under observation, at the sub-atomic level.