1. Physics and the Quantum Mechanical Model Notes

2. Light and the Atomic Spectrum Light is composed of waves at different wavelengths The wave is composed of: –Wavelength (λ): is the distance between the crests –Frequency (ν): the number of wave cycles to pass a point per time –Amplitude: The height of the crest from the origin

3. Waves

4. You can calculate the frequency and wavelength of light using the equation c= λν c = speed of light (3.0 x 10 10 cm/s or 3.0 x 10 8 m/s) λ = wavelength (cm or m – distance between crests) ν = frequency (1/s or s -1 = hertz = Hz)

5. Electromagnetic Spectrum Visible Light is composed of a small section of the Electromagnetic Spectrum EMS- a scale of all forms of radiation that exhibit wave-like behavior as they travel through space Light can be broken up into a spectrum of colors (ROY G BIV) red – orange - yellow – green – blue – indigo- violet Violet is the highest energy (shortest wavelength) Red is the lowest energy (longest wavelength)

6. Electromagnetic Spectrum (EMS)

7. Types of Spectra

8. Continuous: Produced by a hot, opaque (dense gas or solid). A RAINBOW of colors Emission/Dark Line: Produced by a hot, transparent gas Absorption: Produced by a cool, transparent gas

10. Atomic Emission Spectrum Each element has its own unique emission spectrum when it is excited Excitation is usually induced via heat, electricity, etc. Excited = move up an energy level (absorb a “quanta” of energy. When e moves back to ground state, a quanta of energy (called a PHOTON is released

11. Quanta = “Packet” of Energy Photon: “particle” of electromagnetic radiation. ZERO mass, carries a quantum (amount) of energy When an electrons falls back to it’s natural (non “excited state”) it’s seen a light and felt as heat

12. Photoelectric Effect (Solar Cells) Metals eject electrons called photoelectrons when light shines on them (energy not emitted continuously) Plank showed relationship between the intensity of light shined on metal (frequency) and amount of electrical current produce (Energy).

13. Plank’s Constant E = h x v E = radiant energy h = 6.6262 x 10 -34 Jxs (Plank’s Constant) = Energy of one photon v = frequency of the radiation (Hz) Frequency (v) and Energy (E) directly proportional!

14. De Broglie equation Wave-particle duality: Particles exhibit wave and particle properties (not just light but ALL matter) λ = h / mv m = mass of particle h = 6.6262 x 10 -34 Jxs (Plank’s Constant)

15. Atomic Emission Spectrum