1. Unit 1 – Atomic Structure Lesson 1: The Electromagnetic Spectrum

2. Wavelength & Frequency Wavelength – Measured in nm  distance between 2 peaks

3. Frequency Measured in Hz  # of wavelengths passing a given point in a second

4. Electromagnetic Spectrum As wavelength decreases, frequency increases

5. Types of Radiation Gamma Rays – Highest frequency – Sources: nuclear reactions, outer space – Have enough penetrating ability to pass through 3 meters (9 feet!) of concrete – In large amounts can cause radiation poisoning – When controlled, can be used to help cure some cancers

6. X-Rays – Extensively used in the medical field – Uncontrolled exposure to x-rays, can lead to mutations or cell damage – Used by geologists & chemists for characterizing the structure & properties of crystalline materials Types of Radiation

7. UV – Some exposure promotes Vitamin D production and tanning – Too much can lead to sunburn, retina damage and cancer Types of Radiation

8. More UV uses – Kills micro-organisms in water and food – Hardens casts – Insects & birds use UV for navigation

9. Infrared (IR) – Molecules existing above absolute zero (-273 Celsius) all emit IR, recorded as heat – ½ of the Sun’s energy is emitted in the IR region – Tungsten light bulbs are inefficient. They produce more IR than actual visible light Types of Radiation

10. Infrared Cont’d

11. Types of Radiation Microwaves – Highest frequency – Emitted by Earth, buildings, cars, planes – Low level radiation in space

12. Radio waves Types of Radiation

13. Visible light (radiation our eyes see) – Ranges from 780 nanometers (deep red) to 400 nanometers (violet) – ROYGBIV – Also called a “continuous spectrum

14. Visible light cont’d

15. Electrons travel in specific orbits Emit light when they give off the energy they acquired & fall back to their original orbit

17. Spectroscopy Emission – Study of the line spectra given off by electrons returning to their original energy level Absorption – Study of the dark lines of a spectra which represents the energy that was absorbed by a sample

19. The Glowing Pickle! http://www.youtube.com/watch?v=QZieGLO9 _ks http://www.youtube.com/watch?v=QZieGLO9 _ks

20. Historical Development of The Atomic Model John Dalton (1766-1844) – English school teacher, interested in chemistry, physics and meteorology – Developed atomic theory – Published the first list of atomic weights – Died in 1844 after suffering from repeated strokes for over 7 years, although he continued to contribute effectively to science

21. Dalton’s Atomic Theory 1.All elements are composed of tiny, indivisible particles called atoms 2.Atoms of the same element are identical and those of different elements are different 3.Atoms of different elements can physically mix together or chemically combine in simple whole number ratios to form compounds

22. 4. While chemical reactions occur when atoms are separated, joined, or rearranged, atoms of one element are never changed into atoms of another element as a result of a chemical reaction

23. JJ Thomson (1856-1940) Plum pudding model

24. Ernest Rutherford (1871-1937) “gold foil experiment”

25. Neils Bohr (1885-1962) Proposed electrons are arranged in orbits

26. -Electrons cannot exist between energy levels -To move up an energy level an electron must gain enough electricity -When it loses this acquired energy, it moves back down to its original energy level

27. Increasing energy Energy Levels

28. Louis de Broglie (1892-1987) Wave particle theory Related circumference of orbit to whole number wavelengths of an electron travelling around the nucleus

29. Erwin Schrodinger (1887-1961 Defined the probability of finding an electron around the nucleus