1. Chapter 5
Electrons in Atoms

2. I. The Dual Nature of Matter
Matter and energy
are related 2
E=mc
B. As matter gets smaller it behaves more like energy
"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality."--Albert Einstein

3. C. Scientists in the early 1900’s observed that elements emitted unique frequencies of visible light when heated with a flame

4. D. Electromagnetic radiation – form of energy that exhibits wavelike behavior
Visible light is a type of electromagnetic radiation
To understand how small amounts of matter ( like electrons) behave we must study wave properties

5. II. The Wave Nature of Light

6. The Electromagnetic Spectrum
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7. II. Wave Nature of Light

8. The wavelength, the frequency, and the speed of light obey the following relationship:
wavelength * frequency = speed of light.
The speed of light is usually represented by c, the wavelength by the lower case Greek letter lambda, l and the frequency by lower case Greek letter nu n. In these symbols, the above formula is:
l n = c

9. Max Plank
In his research on the radiation from a hot (black) body, Max. Plank made a simple proposal.
He suggested that light consists of photons.

10. The energy, E, of each individual photon of a monochromatic light wave, is proportional to the frequency, n, of the light:
E = h n
where h (= 6.626*10-34 J s) is now known as the Planck constant. Often, we write h = 6.626e-34 J s for simplicity.

11. deBroglie Proposal
Appealing to symmetry of nature, deBroglie proposed that electrons, too, have a wave nature and a wavelength!
In particular, deBroglie proposed that the wavelength of a body could be found from
                     

12. Flame Test Lab Questions
Put the unknowns in order from high to low energy.
Explain why the order makes sense according to what you know about wavelength.
Why do the different elements in the lab emit different frequencies of light.

13. Electron Configuration Notation
Aufbau principle – electrons occupy the lowest energy orbital possible
Pauli exclusion principle – if two electrons occupy the same orbital they must have opposite spins (no two electrons can have the exact 4 same quantum numbers)
Hundz rule – electrons occupy orbital within a sub-shell singly until they have to pair