Electrons in atoms ppt

atoms electron microscope image and electrons atoms and molecules in inorganic chemistry
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Dr.SamuelHunt,United Arab Emirates,Teacher
Published Date:21-07-2017
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Chapter 9 Electrons in Atoms and the Periodic TableClassical View of the Universe • Since the time of the ancient Greeks, the stuff of the physical universe has been classified as either matter or energy. • Matter is has to have mass and volume • Energy, is not composed of particles. • Energy can only travel in waves. www.ThesisScientist.comThe Nature of Light—Its Wave Nature • Light is a form of electromagnetic radiation. • Electromagnetic radiation is made of waves called photons; traveling at ―c‖ • Electromagnetic radiation moves through space like waves move across the surface of a pond www.ThesisScientist.comSpeed of Energy Transmission www.ThesisScientist.comElectromagnetic Waves • Every wave has four characteristics that determine its properties: wave speed, height (amplitude), length, number of wave peaks that pass in a given time. • All electromagnetic waves move through space at the same, constant speed. 8 3.00 x 10 meters per second in a vacuum = The speed of light, c. www.ThesisScientist.comCharacterizing Waves • The amplitude is the height of the wave.  The distance from node to crest.  The amplitude is a measure of how intense the light is—the larger the amplitude, the brighter the light. • The wavelength (l) is a measure of the distance covered by the wave.  The distance from one crest to the next. Or the distance from one trough to the next, or the distance between alternate nodes. It is actually one full cycle, 2π  Usually measured in nanometers. -9 1 nm = 1 x 10 m www.ThesisScientist.comElectromagnetic Waves www.ThesisScientist.comCharacterizing Waves • The frequency (n) is the number of waves that pass a point in a given period of time. The number of waves = number of cycles. -1 Units are hertz (Hz), or cycles/s = s . -1 1 Hz = 1 s • The total energy is proportional to the amplitude and frequency of the waves. The larger the wave amplitude, the more force it has. The more frequently the waves strike, the more total force there is. www.ThesisScientist.comLow Frequency Wave l l High Frequency Wave l www.ThesisScientist.comThe Electromagnetic Spectrum • Light passed through a prism is separated into all its colors. This is called a continuous spectrum. • The color of the light is determined by its wavelength. www.ThesisScientist.comColor • The color of light is determined by its wavelength.  Or frequency. • White light is a mixture of all the colors of visible light.  A spectrum.  RedOrangeYellowGreenBlueViolet. • When an object absorbs some of the wavelengths of white light while reflecting others, it appears colored.  The observed color is predominantly the colors reflected.  Called transmitted light www.ThesisScientist.comTypes of Electromagnetic Radiation • Classified by the Wavelength Radiowaves = l 0.01 m. Low frequency and energy. -4 -2 Microwaves = 10 m l 10 m. -7 -5 Infrared (IR) = 8 x 10 l 10 m. -7 -7 Visible = 4 x 10 l 8 x 10 m. ROYGBIV. -8 -7 Ultraviolet (UV) = 10 l 4 x 10 m. -10 -8 X-rays = 10 l 10 m. -10 Gamma rays = l 10 . High frequency and energy. www.ThesisScientist.comElectromagnetic Spectrum www.ThesisScientist.comParticles of Light th • Scientists in the early 20 century showed that electromagnetic radiation was composed of particles we call photons. Max Planck and Albert Einstein. Photons are particles of light energy. • One wavelength of light has photons with that amount of energy. www.ThesisScientist.comThe Electromagnetic Spectrum and Photon Energy • Short wavelength light have photons with highest energy = High frequency Radio wave photons have the lowest energy. Gamma ray photons have the highest energy. • High-energy electromagnetic radiation can potentially damage biological molecules. Ionizing radiation The waves fit between atom-atom bonds, and vibrate/shake the atoms loose www.ThesisScientist.comOrder the Following Types of Electromagnetic Radiation: Microwaves, Gamma Rays, Green Light, Red Light, Ultraviolet Light, Continued • By wavelength (short to long). Gamma UV green red microwaves. • By frequency (low to high). Microwaves red green UV gamma. • By energy (least to most). Microwaves red green UV gamma. www.ThesisScientist.comLight’s Relationship to Matter • Single atoms can acquire extra energy/photons, and then they release it. • When atoms emit back energy, it usually is released in the form of light. • However, atoms don’t emit all colors, only very specific wavelengths.  In fact, the spectrum of wavelengths can be used to identify the element. www.ThesisScientist.comEmission Spectrum www.ThesisScientist.comSpectra www.ThesisScientist.comAbsorption spectrum Emission spectrum Absorption spectrum 656.3 486.1 434.1 410.2 Emission spectrum www.ThesisScientist.com

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