1. Waves & Particles  Electromagnetic Radiation  Is a fancy term for LIGHT  Human eyes only detect a very small range of colors, so we tend to not think of the others as “light” but they definitely are. LPChem:Wz:1415

2. Electromagnetic Radiation: Light zIs a type of energy zPropagates as a wave LPChem:Wz:1415 Wavelength = (Greek lambda) Measured in meters Frequency = (Greek nu) Measured in 1/s or Hertz (Hz)

3. Electromagnetic Spectrum: LPChem:Wz:1415 The Electromagnetic Spectrum (all the “colors” of light) ROYGBV High Energy Low Energy

4. Electromagnetic Radiation: Light zWavelength and frequency are inversely proportional yAs wavelength increases, frequency decreases (and vice versa. LPChem:Wz:1415 c =  c = the speed of light: 3.0 x 10 8 m/s The speed of light is a constant. 3.0 x 10 8 m/s will be the value of “c” whenever you solve this equation.

5. Electromagnetic Radiation: Light zA certain Utah radio station broadcasts at 99.5 FM zFM radio stations give their frequencies in megahertz  99.5 FM = 99.5 x 10 6 Hz = frequency (  yWhat is the wavelength used by this radio station? LPChem:Wz:1415 c =  3.0 x10 8 m/s =  99.5 x 10 6 Hz1/s 3.0 x10 8 m/s 99.5 x 10 6 1/s = = 3.02 m The radio waves that 99.5 FM broadcasts on are 3 meters long.

6. Electromagnetic Radiation: Light zFrequency and ENERGY are directly proportional yAs frequency increases, the energy of the light increases. LPChem:Wz:1415 E = h  h = Planck’s Constant: 6.626 x 10 -34 J  s This number will be the value of “h” whenever you solve this equation. E is energy (in Joules) is still frequency (in Hz or 1/s)

7. Electromagnetic Radiation: Light zWhat is the Energy of the light (radio) wave 99.5 FM broadcasts on? LPChem:Wz:1415 E = h  E = 6.626 x 10 -34 J  s  99.5 x 10 6 Hz 1/s E = 6.59 x 10 -26 J 99.5’s radio signal is carried by waves of light with an energy of 6.59 x 10 -26 J. Why so little energy? That is the energy generated by just ONE electron in ONE atom.

8. Energy in the Atom zElectrons in the atom are in different Energy Levels (n) yOrbitals further from the nucleus have higher energy yElectrons can absorb light to jump up to a higher energy level. yElectrons can emit light to jump down to a lower energy level. LPChem:Wz:1415

9. Energy in the Atom zElectrons are most stable at the lowest available energy (ground state) and will always return to ground as soon as possible. yAny level above ground state is considered an “excited state” yThe electron is “excited” when above ground state. LPChem:Wz:1415

10. Energy in the Atom zAn electron moves from n = 1 to n = 3 yEnergy must be absorbed zAn electron moves from n = 2 to n = 1 yEnergy must be emitted zEnergy is conserved in all these changes! LPChem:Wz:1415

11. Each element gives off (and absorbs) a unique set of wavelengths. These spectra are used as “fingerprints” to identify elements. LPChem:Wz:1415