Modern Atomic Model and EMR

1. Modern Atomic Model and EMR

2. Describe the electromagnetic spectrum in terms of frequency, wavelength, and energy. • Use Plank’s equationand the speed of light to solve equations for electromagnetic waves. Additional KEY Terms Spectroscopy Emission Quantum Line spectrum

3. Maxwell (1860) - all energy radiated from objects (including visible light) is electromagnetic radiation. Composed of radiated waves of both electrical and magnetic energy.

4. Wavelength(λ - “lambda”): distance from one crest to the next crest or trough to trough. Frequency(ν – “nu” or ƒ): number of wavelengths, or cycles, that pass a point per unit time. Frequency is measured in cycles per second (s-1), or the SI unit hertz (Hz). Amplitude: height of the wave from origin to crest.

5. Types of Electromagnetic radiation

6. All EMRradiates at 3.00 x 108 m/s in a vacuum. This universal value (c) is a product of the wavelength and frequency of the radiated energy. “speed of light” c = λƒ c = λν Wavelength and frequency are inversely related. Wavelength and frequency do not affect amplitude.

7. Sunlight (white light) shone through a prism separates into a continuousspectrum of colours. Each colour represents light of a different frequency – increasing frequency - ROYGBIV

8. Planck(1900) Elements give off a unique colour of light when burned - used to detect the presence of a metal This is known as a If the light emitted is focused through a prism, a spectrum with distinctlinesis produced.

9. Disclaimer – This is not as simple as my drawing.

10. Energy emitted by a heated element can be separated – producing emission spectrum. (line spectrum)

11. C O The colored lines of the atoms (or Spectral Lines) are a kind of "signature" for the atoms.

12. Spectroscopy and spectrophotometry are techniques used to determine a substance’s emission spectrum

13. Planck's law: postulated that energy can only be gained or lost in discrete amounts – quanta. Quantum is the minimum amount of energy gained or lost by an atom. Energy contained in a quantum was directly related to the frequency of radiation emitted. E = hf

14. E = hf E – energy of a quantum (Joules) h – Plank’s constant (6.626 x 10-34 J s) f – frequency of absorbed or emitted EMR

15. The colours seen in fireworks are a result of burning different salts. Red light has a wavelength of 650 nanometres. Calculate the frequency of red light (1 nm - 1.0 x 10-9m). c = λ ƒ ƒ = 3.00 x 108 m/s 650 x 10-9 m ƒ = 4.6 x 1016 Hz

16. The blue colour of fireworks is often achieved by heating copper (I) chloride to about 1200oC. The wavelength of the blue light is 450 nm. What is the quantum of energy emitted by this light? ƒ = c ƒ = 3.00 x 108 m/s λ 450 x 10-9 m E = hf ƒ = 6.7 x 1014 Hz E = (6.626 x 10-34J·s)(6.7 x 1014 Hz) E = 4.4 x 10-19J q

17. CAN YOU / HAVE YOU? • Describe the electromagnetic spectrum in terms of frequency, wavelength, and energy. • Use Plank’s equationand the speed of light to solve equations for electromagnetic waves. Additional KEY Terms Spectroscopy Emission Quantum Line spectrum