I II III  Suggested Reading Pages  Section 4-2 Quantum Theory

 Came about because classical physics couldn’t explain everything.  Why does a metal emit invisible radiation first (IR – heat) and then glow red, and then yellow, and then white? Quantum Theory

Quantum Mechanics

Heisenberg’s Uncertainty Principle  There is a limit to just how precisely we can know both the position and velocity of a particle at a given time.

 Diffraction: The bending of a wave as it passes by the edge of an object or through a small opening. de Broglie – electrons have wave-like properties. Interference: occurs when waves overlap.

 Regions around the nucleus of an atom where an electron with a given energy is likely to be found. Atomic Orbital's (electron clouds)

Quantum Numbers  Describe orbital's and electrons in them  1 st Quantum # = main energy level (n)  2 nd Quantum # = shape ( l )  3 rd Quantum # = which way it’s pointing(m l )  4 th Quantum # = which way it’s spinning(m s )

principal quantum number “n”  Main Energy Level  Higher “n” = more energy = farther from nucleus

Angular momentum quantum number “ ”  Has to be lower than 1 st quantum #  Indicates shape  = 0 s shaped contains 1 orbit  = 1p shaped contains 3 orbits  = 2d shaped contains 5 orbits  = 3f shaped contains 7 orbits

 s orbitals Shapes of Orbitals

 p orbitals Shapes of Orbitals

 d orbitals Shapes of Orbitals

 f orbitals Shapes of Orbitals

Magnetic quantum number “m ”  Tells which way it’s pointed

Possible Values of m  s = 0  p = -1, 0, +1  d = -2, -1, 0, +1, +2  f = -3, -2, -1, 0, +1, +2, +3

Spin quantum numbers m s  Represented with up or down arrow  Can only be +½ (pointed up) or -½ (pointed down)

 The rule states that no two electrons may ever have the same four quantum numbers. Pauli exclusion principle

4 Minute Review