3Background Neils Bohr Danish Physicist Proposed a “planetary” model of the atomTheorized thattravel in orbits aroundthe nucleus
4Electrons in Orbit?Bohr suggested that electrons “jump” between energy levels (orbits)When an atom absorbs or gives off energy, the electron jumps to a higher or lower orbit.It absorbs energy as it moves up to a higher orbitIt gives off energy as it moves down to a lower orbitThis energy is given off as heat or lightThis energy given off travels in the form of wavesAlso called an emission of an photon
7To calculate the amount of energy between energy levels: Just subtract the initial energy state from the final.E5 to E1:_-.54______ - _-13.6___ = 13.06E3 to E1:_-1.51__- _-13.60___= 12.09E4 to E2:_-.85_-__-3.40__= 2.55E5 to E2:_-0.54__-_-3.40__= 2.86410mnE5434mnE4E3486mnE2656mnE1+EE -3.40_________________________________E -1.51E -0.85E – 0.54
8_________________________________ 400 500 600 700 E -0.85 E – 0.54 410mnE4434mnE3486mnE2656mnE1+EE -3.40E -1.51_________________________________E -0.85E – 0.548
10The Electromagnetic Spectrum You actually know more about it than you may think! The electromagnetic spectrum (EM) is just a name that scientists give all the different types of radiation when they want to talk about them as a group.Radiation is energy that travels and spreads out as it goesvisible light that comes from a lamp in your houseradio waves that come from a radio stationHotter, more energetic objects and events create higher energy radiation than cool objects.
11Wavelength isthe distance from crest tocrest of a waveThe frequency of a wave is the number of waves that pass a given point one second
12Electron Energy The longer the wavelength the lower frequency The shorter the wavelength the higher the frequency
13The Electromagnetic Spectrum Radio:the same kind of energy that radio stations emit into the airalso emitted by stars and gases in spaceHelps astronomers learn what they are made of.Microwaves:They will cook your popcorn injust a few minutes!Microwaves in space are usedby astronomers to learn aboutthe structure of nearby galaxies,our own Milky Way!
14Infrared:Our skin emits infrared lightIn space, Infrared light maps the dust between stars
15The Electromagnetic Spectrum Visible Light:This is the only section of the EM that can be seen by our eyes.Visible radiation is emitted by everything from fireflies to light bulbs to stars ... also by fast-moving particles hitting other particles.
16The Electromagnetic Spectrum Ultraviolet:The Sun is a source of ultraviolet(or UV) radiationStars and other "hot" objects inspace emit UV radiation.X-rays:Your doctor uses them to look at your bones and your dentist to look at your teeth.Hot gases in the Universe also emit X-rays .
17Gamma Rays:Radioactive materials (some natural and others made by man in things like nuclear power plants) can emit gamma-rays.Big particle accelerators that scientists use to help them understand what matter is made of can sometimes generate gamma-rays.