c = speed of light (ms-1, constant) Electromagnetic Radiation  c/  = wavelength (m)  = frequency (Hz = s-1) c = speed of light (ms-1, constant) c = 3.00*108 ms-1 we say: 1/ Point A

Electromagnetic Spectrum When do we see white? All wavelengths of the visible spectrum (ROYGBV) and equal amounts of RGB (look at your TV) hc  1  E = ; E  saunders 7-4

The Photoelectric Effect Exp: A metal plate is exposed to electromagnetic radiation (Light) and a detector is used to determine if electrons are ejected from the metal. Classical Theory states that even if low energy light is used the electrons should eventually be ejected. Exp. results did not agree. Exp. results showed that only light of sufficient energy would eject electrons from the metal and each metal required a different energy. Albert Einstein - explained this result using Planck’s idea that light also behaves like particles (photons) and that each particle has a specific (quantum) amount of energy. Intensity of light - # of photons striking a given area of the plate per second

Atomic Spectrum Emission spectrum Balmer Series 1 1 R=rydberg pg. 202 Enrichment 1 n12 1 n22 R=rydberg constant n1 < n2

Bohr Model n=3 n=2 n=1

Wave Nature of Electrons h mv  = Louis de broglie saunders 7-8

Heisenberg Uncertainty Principle It is impossible to determine accurately both the momentum and the position of a very small particle (electron) simultaneously

Quantum Mechanics Atoms and molecules can exist only in certain energy states (quantized energy levels) When they change their state they absorb or emit radiation (light/photons) E = hc/ Allowed energy states are described by 4 quantum numbers

Principle Quantum Number - n = 1, 2, 3 .... Describes the main energy level and the extent of the orbital Angular Momentum Quantum Number - l = 0, 1, 2, ... , (n - 1) Describes the shape of the orbital l = 0 s orbital, l = 1 p orbital, l = 2 d orbital, l = 3 f orbital, l = 4 g orbital, l = 5 h orbital ..... Magnetic Quantum Number - ml = -l, -l+1 , ... , 0 , ... , l-1 , l Describes the orientation of each orbital Spin Quantum Number - ms - ±(1/2) Describes the spin of the electron in each orbital