Mr. Sexton's Science Outpost

Nature is worth knowing.

Chemistry Students Explore Atomic Emission Spectra

    According to the Bohr model of the atom, electrons are confined to orbits with fixed distances around the nucleus that correspond to specific levels of energy.  Higher energy levels are located farther from the nucleus. When atoms are bombarded with energy, each electron can only absorb the precise quantum of energy needed to move from its ground state to a higher energy level (excited state).  When electrons fall back to the ground state, this quantum of energy is released as a photon of light.  Each element has a unique set of electrons, and therefore, will emit a unique spectrum of photons.  These emission spectra can be used like a fingerprint to identify an element!  Here’s an animated video that I made of the phenomenon.

For Teachers

What makes this argument-driven inquiry lab unique and challenging for most students is the authentic nature of  the inquiry.  Students were given a question and shown the proper use of laboratory tools, but they were not given a procedure, nor a data table.  By considering what data they would need for their argument, and how they would produce and record their data, they gained a deeper understanding of the subject matter, as well as their skill in the science and engineering practices.

After their plans were approved, students began to energize atoms in a bunsen burner flame and analyze the light with a spectroscope.  The spectroscope separates the photons by diffraction and allows each wavelength to be measured for comparison.  In the photo above you can see by the scale that the bright yellow spectral line has a wavelength of 604 nanometers.  Students collected spectral emissions from a variety of known substances, The Bohr Modeland then unknown substances.  Most were able to use a cell phone to capture images through the spectroscopes.  They collaborated by sharing the data via uploads to Google Drive.  In their notebooks their lab reports will include a scannable QR code that will open the link to their shared photos.  Here is a QR code example that will direct you to the section of my website where resources for this lab are located. There are many websites for generating QR codes. This one was done at QR Stuff

After gathering their evidence, each lab group worked together on a whiteboard to create and share an argument that consists of the following:

  • Their claim – They will answer the question, What are the identities of the unknown substances?
  • Their evidence – They will present their photographs of the emission spectra and measurements of prominent lines.
  • Their Reasoning – They will justify their claim by explaining the significance of their evidence by relating it to the principles and theory they have studied.

After sharing and revising their arguments with other lab groups, each student typed an individual report. Their reports were then edited after a double-blind group peer review.  They submitted their edited final draft through Turnitin.

 

For Students

Here are a few questions for further consideration. Please feel free to comment (extra credit?).

  • In this lab we studied emission spectra.  So what are the differences and similarities between an emission spectrum and an absorption spectrum?
  • We use emission and absorption spectra to study nature at the atomic scale (which is unimaginably small), so how do astronomers use the same phenomena to study the vast universe?
  • What is the relationship between the wavelengths of the spectral lines and their frequency? Can you calculate the frequency for one of the lines in the helium emission spectrum above?
  • What is the relationship between the frequency of the photons and their energy?  Can you calculate the energy for one of the lines in the helium emission spectrum above?
  • What’s up with Planck’s Constant? What does it reveal about the quantum nature of the atom, and the wave-particle duality of light?

 

Winter Solstice

Summer-Solstice-Stonehenge-1024x380Since the neolithic era, the December (winter) solstice has evolved into a time of great significance throughout humanity. In fact the time of the solstice is a common denominator upon which the histories and customs of many major cultures are interwoven.  Here is a link to read more about customs and holidays around the December solstice.

 

EarthWinterSolstice

Click the image for an interactive season simulator.

 

The December solstice marks the day when the tilt of the Earth’s axis points the north pole away from the Sun. During this time, the Sun’s rays are at their most indirect angle as they strike the northern hemisphere and the daylight hours are at their minimum. Conversely, the Sun’s rays fall directly upon the Tropic of Capricorn in the southern hemisphere where they experience their summer solstice and maximum daylight hours.
Here is a link to an interactive seasons astronomy simulator that lets you manipulate the date, latitude and the tilt of Earth’s axis to see the effect in seasonal temperatures, daylight hours, and the apparent path of the sun across the sky.

Have a wonderful solstice and a prosperous New Year!

This Wasp Kills Black Widow spiders!

The Blue Mud dauber preys upon Black Widow spiders. Nice! http://en.wikipedia.org/wiki/Blue_mud_dauber

The Blue Mud dauber preys upon Black Widow spiders. Nice!

This is the second metallic green insect that I have found in my backyard over the last few days.  Chalybion californicum is the scientific name of the Blue Mud Dauber. I was lucky to snap a shot of it because they are lightning fast! They range in darkness and in color from blue to green.

Chalybion californicum

Chalybion californicum

Not only do Blue Mud Daubers prey upon Black Widow spiders, but this beauty was kind enough to pause briefly for a photo.  Come back any time little buddy!

 

 

 

 

 

 

Coalinga High School Earns 6-year WASC Accreditation

Western Association of Schools and CollegesHard work and dedication at Coalinga High School lead to a coveted 6 year accreditation from the Western Association of Schools and Colleges.

According to WASC, this accreditation certifies to the public that Coalinga High School is a trustworthy institution of learning, validates the integrity of our school’s program and student transcripts, and assures the communities of Coalinga and Huron that our high school’s purposes are appropriate and being accomplished through a viable educational program.

Receiving a six year WASC Accreditation was the result of hardworking professionals whose leadership and dedication guided our schools process and kept the focus on the care and education of Coalinga High School students,” said Coalinga High School PrincipaI Margo Perkins.  “I look forward to continuing to work with the Leardership Team and staff to make CHS the best school it can be.

GO TOADS!!!

 

Safety First!

Fireworks blow off the hand, fingers of three California men.

 Lit Explosive Fuse Crackling and Sparking fireworks

 

This is why we say ‘Safety First!’ It’s also why we start every year of science at CHS with safety procedures and awareness.

http://sanfrancisco.cbslocal.com/2014/07/05/fireworks-blow-off-hands-fingers-of-3-southbay-men/#.U7n-8PJtQO8.email

Updated: July 6, 2014 — 7:06 pm

Science Daily

Here is one of my favorite website for science articles.

scidaily-logo

Science Daily is a great website for keeping up on the latest science and finding science related articles. As you have probably experienced, students are not always very experience in evaluating the credibility of internet sources. Some nice features are:
1) All articles are second-source reports published only in reputable, peer-reviewed science journals.
2) The articles are categorized and sub-categorized to easily find topics of interest.
3) At the end of each article is a citation that can be automatically formatted in APA or MLA style.
4) There are a variety of RSS feeds to choose from, such as health, technology, environment, etc…

Enjoy!

Mr. Sexton

Updated: July 4, 2014 — 2:58 pm

Match the Molecule

Here are images (DON’T READ THE CAPTIONS YET!) of three important biological macromolecules.

One of them is a nucleic acid.

One of them is a protein (the most abundant protein on Earth!).

One of them is a little bit of both, a ribonucleoprotein.

Can you guess which one is which before you read the captions?

Protein ribbon structure of Rubisco

Rubisco is the nickname of the protein Ribulose-1,5-bisphosphate carboxylase oxygenase

Over the course of evolutionary time, regions of the ribosome in different species have been added while conserving the functional core.

Over the course of evolutionary time, regions of the ribosome in different species have been added while conserving the functional core.

The molecular structure of DNA is like a twisted ladder.

The double helix structure of deoxyribonucleic acid, or DNA, is like a twisted ladder where the sides of the ladder are composed of sugar and phosphate units linked by covalent bonds, and the rungs of the ladder are made of the four nitrogenous bases linked by hydrogen bonds.

Study Reveals Evolution of the Ribosome in New Detail

What good is DNA without a ribosome?  Considering how the ribosome has changed over the last 4 billion years gives insight to the crucial nature of its role in biology, the unity of all life, and the process of evolution.

http://www.sciencedaily.com/releases/2014/06/140630164012.htm

In the new study, Williams and Research Scientist Anton Petrov compared three-dimensional structures of ribosomes from a variety of species of varying biological complexity, including humans, yeast, bacteria and archaea. The researchers found distinct fingerprints in the ribosomes where new structures were added to the ribosomal surface without altering the pre-existing ribosomal core from the last universal common ancestor.140630164012-large

For a video on the origins and evolution of the ribosome, visit:https://www.youtube.com/watch?v=ei6qGLBTsKM

Mr. Sexton's Science Outpost © 2014 Frontier Theme
%d bloggers like this: