4. Complex Knowledge: demonstrations of learning that go aboveand above and beyond what was explicitly taught. 3. Knowledge: meeting the learning goals and expectations. 2. Foundational knowledge: simpler procedures, isolated details, vocabulary. 1. Limited knowledge: know very little details but working toward a higher level.  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 telescopes work  understand how lenses are used in telescopes.

I need to see your labs….  come show me

2/11/2016 BellWork  When looking at the spectrum tubes yesterday and Tuesday, how is what you saw using a diffraction grating or a spectroscope different than what you see with your eyes? What causes that difference?

Finally

Today’s Questions  What can we learn by observing the spectrum of an object?  How do continuous, emission and absorption spectrum differ?

read. answer.  FYI: Spectral Lines

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

TypeInformation Continuous Emission Absorption

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.

Emission Spectra  This is also why different elements will burn with different colors barium a green flame lithium and strontium a red flame calcium an orange flame sodium a yellow flame copper a blue flame

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.  Light is a wave.  Light is a particle. v2Ym8 JXZw

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.

 atoms can also 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  Structure/PlanckQuantized.htm Structure/PlanckQuantized.htm

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

solar spectrum with fraunhofer lines as it appears visually

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

Mystery Star

Homework…Read each tab, and then do the exercises. There will be a test question or two taken directly from this activity…. It wont work on a phone, you need a computer.  Structure/PlanckQuantized.htm Structure/PlanckQuantized.htm