Content Area: Chemistry (10-12th grade)
Topic: Electron Configurations
Sub-Topic: Emission Spectra
Computer requirements: Internet access,
ShockWave Plug-In
Prior content covered: Basic structure of the
atom
Estimated time for computer portion of lesson:
15-20 min
Essential Questions or Ideas
to Address:
- How is the
emission spectra related to electron configurations?
- What does it mean to say that the electron energies are
quantized?
The lesson: (90-min block)
Students observe the emission spectra of several gases in a lab setting
using gas tubes and a diffraction grating slide. Students have recorded
the observed spectra for hydrogen, helium and one or two other gases.
The students then go to the computer lab and working in groups of two
they access the
Visual Quantum Mechanics web-site for emission spectra. They create
energy level diagrams that match those of different gas tubes. On the
recorded diagrams, students color the arrows with a color approximating
the color produced by on the spectrum by that electron.
After they complete several diagrams, they return to the
regular classroom for a discussion of how the spectra provide evidence
for electrons being in orbitals.
Common misconception addressed: Students
often believe that larger energy changes are associated with red and
smaller energy changes are associated with blue wavelengths.
Evaluation of lesson effectiveness: While
students initially have some difficulty with the website, after they
learn the steps to create a diagram, they proceed with facility. Since
this lesson has been in use, very few students have trouble remembering
that high energy emission is purple and low energy is red.
Alternate presentation: This visualization
could easily be part of a lecture discussion.
Extensions:
Students could check out the absorption and emission
spectra applet at
http://jersey.uoregon.edu/vlab/elements/Elements.html
Note: Be sure to check out the other
animations available at the main page for this web site
(
http://phys.educ.ksu.edu/vqm/index.html ).
Standards:
MSDE (from the website as of 9/05) :
| Chemistry/Core Learning Goals |
| Science Indicator 4.2.1
The student will illustrate the structure of the atom
and describe the characteristics of the particles found there. AT
LEAST: protons, neutrons, & electrons, nucleus.
Indicator 4.2.2
The student will demonstrate that the arrangement and
number of electrons determine the properties of an element and that
these properties repeat in a periodic manner illustrated by their
arrangement in the periodic table. AT LEAST: atomic number, mass
number, valence electrons, chemical properties/families
|
Goal 5 Concepts Of Chemistry
The student will demonstrate the ability to use scientific skills and
processes (Core Learning Goal 1) to explain composition and
interactions of matter in the world in which we live.
Expectation 4.2
The student will explain that all matter has structure and the
structure serves as the basis for the properties of and the changes in
matter.
|
National Science Standards (9-12):
Physical Science:
- Structure of Atoms:
Matter is made of minute particles called atoms, and
atoms are composed of even smaller components. These components have
measurable properties, such as mass and electrical charge. Each atom
has a positively charged nucleus surrounded by negatively charged
electrons. The electric force between the nucleus and electrons holds
the atom together.
- Interactions of energy and matter:
Waves, including sound and seismic waves, waves on
water, and light waves, have energy and can transfer energy when they
interact with matter.
AAAS Benchmarks (9-12):
The Physical Setting: Energy
Transformations:
- Different energy levels are associated with different
configurations of atoms and molecules. Some changes of configuration
require an input of energy whereas others release energy.
- When energy of an isolated atom or molecule changes, it
does so in a definite jump from one value to another, with no possible
values in between. The change in energy occurs when radiation is
absorbed or emitted, so the radiation also has distinct energy values.
As a result, the light emitted or absorbed by separate atoms or
molecules (as in a gas) can be used to identify what the substance is.
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