I. Positive and Negatively Charged ParticlesII. TemperatureIII. Black Body RadiationIV. SpectroscopyI. How is Spectroscopy UsefulII. When You See an Emission and Absorption SpectrumIII. The Structure of AtomsIV. The Bohr ModelV. Molecules have their own Characteristic LinesVI. Other Properties of LightI. How is Spectroscopy Usefula. It is useful because by spreading the light out in its different components, you know what is in the objectb. Hot Blackbodies will reveal all the colors of the rainbow’ radiation emitted because this object has Temperaturec. Every object with Temp will emit radiation, and that radiation will be continuous; energy given out at every wavelengthi. The amount of energy is dependent on the objectii. The shape of the intensity that a Blackbody radiates is called a Planck Curve, or a Blackbody curveII. When You See an Emission and Absorption Spectruma. Depends on whether you’re looking at a gas cloud, or if you’re looking at gas in atmosphere of an objectb. If you look at the cloud gas backlit, you would see an absorption spectrum because the cloud of gas has atoms which absorb lighti. Looking at it directly, you will see only the gas, and it’s EMITTING lightii. Lines you see are identical to the lines missing from the lines in the absorption spectrumiii. Emission lines you see depend on what types of gas you are looking at!1. Each line is caused by a different element (elements have fingerprints)c. Kirchoff’s Law 3: cool transparent gas in front of a source (backlit) will make the gas will absorb same radiation, and an absorption line spectrum is produced, a series of dark spectral lines among the colors of continuous spectrum (as aforementioned)III. The Structure of Atomsa. There are allowed “orbits,” where electrons can occupy certain energy levels around the protonb. The electron prefers to be in the GROUND STATE (closes energy state to the proton)i. As electron gets further and further away in its allowed shells or levels, it becomes higher in energy1. N = 2 is second energy level, when bundle of energy is absorbed by electron, it will jump to a third level. There is a PRECISE difference because the photon itself meets the energy requirement for the electron to jumpc. Emission and absorption of light is a continuous processIV. The Bohr Modela. Almost correct idealized picture of what an atom isb. An electron does not occupy a precise orbit; it actually lives in a cloud and there is only a probability that an electron is near a given distance from the protoni. En = 13.6(1- 1/n^2)eVc. Every atom has its structure of energy levels, and structure in terms of transitions between levels that give rise to slightly different energies and wavelengthsV. Molecules have their own characteristic Linesa. Ways molecules can emit radiation:i. Electron transitions:1. Vertical lines on a plotted potential energy diagramii. Vibrational transitions:1. Often occur in conjunction with rotational transitions2. Vibration excitation produces radiation in molecules3. The bond between two atoms acts like a spring and can vibrate quickly (giving off more radiation) or more slowly (giving off less radiationiii. Rotational transitions1. Show different isotopes in the spectraVI. Other Properties of Lighta. Light scatters!i. Why the sun looks red when it sets:1. Atmosphere has many particles thatget hit by light coming from sun, and blue light gets scattered more efficiently than red.2. Blue photons encounter particles and bounce off of them, because particles are tiny and shorter wavelengths of light can get knocked off more easily than longer onesii. It depends on the sizeof theparticles in the atmosphere, which have characteristic sizes. If particles were even smaller, the light will be more violetiii. The red light has longer wavelengths so it doesn’t scatter as much or as often as blue light does, so the red light goes straightthroughthe atmosphere.1. As sun is setting, its light goes through a much longer piece of atmosphere, based on its position. So the light that is left from the sun that we are able to perceive is reddishI. Positive and Negatively Charged Particlesa. Every object we see is made up of positive and negative charged particlesb. Whenever you increase the T of an object, you are actually increasing the average thermal motion between those particlesc. Whenever charged particles oscillate (move rapidly) they emit electromagnetic radiationII. Temperaturea. Temperature: measure of how fast particles are moving in given material being analyzedb. Absolute scale gives more accurate characterization of thermal motion: kelvin scalei. At 0 K, all molecular motion ceases to happenIII. Black Body Radiationa. Ideal object that can absorb every light or energyb. As it absorbs it, it transforms the energy and thermalizes the energy, and emits it back into space in a particular fashionc. Stars are good representations of Black Bodiesd. Blackbody spectrum is determined ONLY by its TEMPERATUREi. Given a certain temperature, a curve (Planck curve) is given to show how much light is being emitted by that particular objecte. Radiation Laws:i. Wien’s Law:the higher the temperature, the more to the left the peak will be1. More ration of SHORTER wavelengths are being emitted (higher temperature, shorter wavelength)2. Lambda of max = .29mm/T (in K)ii. Stefan-Boltzmann Law: Tells how much energy is being emitted when increasing Temperature:1. Curve gets taller and taller as you increase the T2. The peak goes to the left (Wieins) AND the peak gets taller (Stefan-Boltz)3. F = sigma * T^4 (sigma – constant 5.67E-8 W.m^2 * K^4) F = energy per second per unit area4. Two stars with different surface areas and SAME Temp: stars with BIGGER SA will look BRIGHTERIV. Spectroscopya. Dark spots on the ribbon that shows the spectral emissions of the suni. If object is dense, colors not missing. If object is less dense, colors can be missingb. Kirchhoff’s Laws:i. First law: Hot dense objects emit a continuous spectrum1. Light is emitted when an electron jumps down an orbit (shell) and light is absorbed so that an electron can climb up to a higher energy level2. Bigger jumps have higher energy associated with the jumpsa. Blue light emitted for big jumps (UV or X ray emitted from even bigger jumps to higher energy levels)b. Red light emitted from a smaller jump (jumping to a lower energy level)c. Planck’s constant: 6.63E-34 joule seconds (J * s); light comes in packets of energy