Understand the electromagnetic spectrum and how it is organized. Understand what different types of electromagnetic radiation can reveal about astronomical objects. Understand and describe important properties of electromagnetic radiation. Understand how technology is used to collect electromagnetic radiation and turn it into images. Understand what can be learned from analyzing the light from astronomical objects. Understand how different types of lenses and telescopes work Understand and describe the quantization of energy at the atomic level Understand that all objects emit and absorb electromagnetic radiation and distinguish between objects that are blackbody radiators and those that are Qualitatively describe the shift in frequency in sound or electromagnetic waves due to the relative motion of a source or a receiver

read. answer.

Finally Spectrum Analysis

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Today’s Question What can we learn by observing the spectrum of an object?

3 types of spectra Continuous Emission (bright line) Absorption (dark line)

Type Information Sketch Continuous Emission Absorption

3 types of spectra – sketch them Continuous Emission (bright line) Absorption (dark line)

Continuous spectra Continuous spectra are emitted by any object that radiates heat (has a temperature). The light is spread out into a continuous band with every wavelength having some amount of radiation. For example, when sunlight is passed through a prism, its light is spread out into its colors.

Emission spectra emission spectra occur when the atoms and molecules in a hot gas emit extra light at certain wavelengths, causing bright lines to appear in a spectra. Like absorption spectra, the pattern of these lines are unique for each element, similar to a fingerprint. We can see emission spectra from comets, nebula and certain types of stars.

This is why you saw those lines in the lab. extra light at certain wavelengths, causing bright lines to appear in a spectra.

Absorption and Emission Spectrums are inverses of each other

Absorption spectra the pattern of dark lines or bands that occurs when light is passed through an absorbing medium into a spectroscope The pattern of these lines is unique to each element and tells us what elements make up the atmosphere of the object. We usually see absorption spectra from regions in space where a cooler gas lies between us and a hotter source. We see absorption spectra from stars, planets with atmospheres, and galaxies.

All the Colors of the Sun If you look more closely at the Sun's spectrum, you will notice the presence of dark lines. These lines are caused by the Sun's atmosphere absorbing light at certain wavelengths, causing the intensity of the light at this wavelength to drop and appear dark. The atoms and molecules in a gas will absorb only certain wavelengths of light.

Why is this happening? Because Light is a wave. AND IT IS A PARTICLE https://www.youtube.com/watch?v=Q_h4IoPJXZw https://www.youtube.com/watch?v=_riIY-v2Ym8

Light Light is created when an electron moves from a higher energy level to a lower energy level. The photon (or particle of light) emitted has an energy that corresponds exactly to the difference in energy between the two levels.

Chemical Fingerprints Because all elements have different atomic structures the electrons around the nucleus emit photons at frequencies that are very characteristic of that particular atom The bright line and dark line (emission and absorption) spectrum is a chemical fingerprint for the element in question.

Emission Spectra of every element

atoms can absorb and emit packets/particles/photons of electromagnetic radiation. the light has discrete energy dictated by the detailed atomic structure of the atoms everything in nature strives to be at its most stable, lowest-energy state, so “excited” or energized electrons will move back down toward their stable shell in small jumps.

Online activity http://www.kentchemistry.com/links/AtomicStructure/PlanckQuantized.htm

solar spectrum with Fraunhofer lines as it appears visually

Mystery Star

Mystery Star

Mystery Star

Mystery Star

We know the exact wavelengths for every single one of these Fraunhofer lines. We can tell exactly what elements are in the sun’s atmosphere.

Please go back and answer today’s (and Thu. and Fri. question What can we learn by observing the light (spectrum) of an object?

Homework…Read each tab, and then do the exercises on the 4th tab Homework…Read each tab, and then do the exercises on the 4th tab. There will be a test question or two taken directly from this activity…. http://www.kentchemistry.com/links/AtomicStructure/PlanckQuantized.htm