2 Fireworks VideoAs you watch this video, answer the questions on your notes page.
3 Electromagnetic Radiation A form of energy that exhibits wavelike behavior as it travels through spaceExamples: Visible light, microwaves, x-rays, radio and television wavesDifferent forms of electromagnetic radiation can be seen on the electromagnetic spectrum
4 Electromagnetic Spectrum Encompasses all forms of electromagnetic radiation, showing the differences of wavelength and frequency in the types of radiation
5 Electromagnetic Spectrum Increasing Frequency Decreasing Wavelength
6 Characteristics of Waves Wavelength ( λ ) – shortest distance between 2 equivalent points on a continuous waves (from crest to crest or from trough to trough)Units of wavelength:Usually in meters,centimeters ornanometers
7 Comparing Wavelengths Which wave has a longer wavelength?Which wave has the shorter wavelength?long wavelengthcrestWavelengthWavelengthtroughshort wavelength
8 Characteristics of Waves Frequency ( v ) – number of waves that pass a given point per secondUnits of frequency:waves per second1 / s = s -1 = Hertz
9 Another way to look at Frequency These 2 waves are traveling at = speeds…more crests cross the ‘finish line’ in a matter of one min.?which wave will havelow frequency= long wavelengthhigh frequency= short wavelength
10 Characteristics of a Wave Amplitude – wave’s height from the origin of the wave to the crest or from the origin to the troughorigin
11 Parts of a waveLabel wavelength, peak, trough and amplitude on the following wave:peakwavelengthamplitudetrough
12 Picking back upElectromagnetic radiation - a form of energy that exhibits wavelike behavior as it travels through spaceElectromagnetic Spectrum - Encompasses all forms of electromagnetic radiation, showing the differences of wavelength and frequency in the types of radiationWavelength ( λ ) – shortest distance between 2 equivalent points on a continuous wavesFrequency ( v ) – number of waves that pass a given point per secondAmplitude – wave’s height from the origin of the wave to the crest or from the origin to the trough
13 Let’s Practice! Study Guide page 25, #1-8. Energy Wave Light Speed WavelengthAmplitudeFrequencyHertz
14 Can we do some more? Yes, we can! Page 25, questions 9-11.A and CB2 hertz
15 Wave CalculationsAll electromagnetic waves travel at the speed of light in a vacuumSpeed of light (c) = 3.00 x 108 m/sSpeed of light is equal to product of wavelength and frequencyc = λ v
16 To solve for…. To solve for wavelength: λ = c / v To solve for frequency: v = c / λ
17 Wave Calculations Practice Calculate the υ of a wave that has a wavelength of 5.00 x 10-6 m.νc=λν3.00 x 108 m/sec5.00 x m==6.00 x HzνWhat is the λ of radiation with a frequency of 1.50 x 1013 Hz?cλ=νλ=3.00 x m/sec1.50 x Hzλ=2.00 x m
18 Emissions of light by atoms all elements will emit light when excited (i.e. by electricity).atoms absorb energy and then emit an equal amount of energy in the form of electromagnetic radiation (i.e. light).- atoms emit a characteristic wavelength- Ne = orange - red- Na = bright yellowif we pass this light through a prism (separate the λ) we get anatomic emission spectrum.ex. of wavelengths emitted
19 Atomic Emission vs. Continuous emission spectra are unique to particular elements.only show certain lines of the continuous spectrum (white light).have helped us gather a lot of info. about our universe!atomic absorption spectra shows colors missing from thecontinuous spectrum (missing λ were absorbed by the element).continuousabsorptionemission
20 Atomic Emission Spectrum The set of frequencies ofthe electromagnetic wavesemitted by atoms of theelementConsists of several linesof color and not a continuousrange
22 Quantum of Energye- are found on certain energy levels (orbitals) around the atom.there is a maximum of seven energy levels in an atom.e- on the energy level closest to the nucleus have the lowest energy.The 7th energy level has the highest energy.- An e- requires one ‘quanta’ (minimum amount of energy gained or lost by an electron) of energy to jump to the next energy level.
23 e- at their lowest energy level are considered to be at the ground state (most stable).if e- absorb a quantum or more of energy (from electricity), they can jump to higher energy levels (excited state).e- must lose energy in order to fall from the excited state back to the ground state.- this energy is emitted in the form of electromagnetic radiation (sometimes visible)!
24 Energy Levels Principal quantum number = = Electrons= Protons= NeutronsIf there are seven energy levels possible, do you think you can tell how many energy levels there would be in at atom based on looking at the periodic table?Principal quantum number =Period number on periodic table