Download electron arrangement in atoms

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PROGRAM CONTENT
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Structure" and precedes "Bonding".
Introduction: The role of electron arrangement in
Chemistry.
Teacher's Notes
ELECTRON
ARRANGEMENT
IN ATOMS
Years: 11-12
Section 1:
Ionization of atoms by electron
bombardment.
Section 2:
Light emission from excited atoms.
Section 3:
Diffraction of electrons.
Section 4:
Quantum mechanics and atomic
orbitals.
Section 5:
The periodic nature of electron
configuration of the elements.
Section 6:
Hydrogen gas and helium gas. How
do the electron configuration of the
atoms and the properties of these
gases reflect one another?
Suggestions on using the Video
Educational research shows that videos are most
effective if shown in short "topic segments". The
audience should be kept in an "active processing" mode
by being required to:
• answer specific questions known to them before
the video is presented;
•
Questions
1.
What is the main difference between the
mechanical and the quantum mechanical
models of an atom?
2.
Write an equation for the third ionization of
calcium.
Duration: 27 minutes
Introduction
For chemists, predictive and intuitive skills with real chemicals
and materials relies on an understanding of electrons in atoms
and molecules learnt from experiments.
This video describes three experiments that can be done in a
student laboratory and some Quantum Theory for chemistry
students.
Experiments similar to the ones shown here have played a vital
role in the evolution of a consistent model of electrons in
atoms which coincides with the Periodic Table of Elements and
other observations of the properties of matter.
In conclusion, students are asked to use their knowledge of
the electron configuration of the hydrogen and helium atoms
to distinguish between the gases.
This video follows on from "The Nature of Matter - Atomic
label key diagrams shown in the video.
The key diagrams are included in these notes for
photocopying for students. Some questions you might
like the students to consider are listed below.
3.
Describe the pattern of successive ionization
energies from Ca to Ca 20+.
4.
Write out the electron configuration of an atom
with 24 electrons.
5.
Which is more energetic - green light or infrared
radiation (heat)?
6.
Which has the shorter wave length - ultraviolet
or violet light?
7.
How would you distinguish between a balloon
filled with neon and one filled with hydrogen?
Would you expect the wave-like properties of
protons and neutrons to be important in
describing their behaviour?
8.
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Section 1: Ionization of Atoms by Electron Bombardment
Interpreting a graph is a vital skill for science students.
Here, the limits of the information available have been
stressed along with the strength of the pattern. The
fundamental electrical repulsion between electrons and
their attraction for protons in the nucleus are reflected in
the results. The conventions for writing electron
configurations are illustrated for the calcium atom.
Section 2: Light Emission from Excited Atoms
A hand spectrometer can be an absolute delight in the
hands of a careful observer. There is detail here about
rainbows and coloured light to emphasise the process
being observed. The actual observation of line spectra
can be startling - it's as if the atoms had signed their name!
The difference between an absorption and an emission
spectrum is illustrated with an explanation of line spectra
in terms of discrete energy levels and electron transitions
between levels.
The hydrogen spectrum and Bohr's theoretical explanation
of it are followed through up to De Broglie's suggestion
that electrons had wave-like properties.
Section 3: Diffraction of Electrons
The experimental conditions which demonstrate diffraction
for beams of light and x-rays is shown in some detail and
then a beam of electrons is substituted.
The observation made first in 1927 by C J Davisson and L
H Gerner that electrons are diffracted in the manner of
waves by an appropriately spaced grating is shown to
introduce the idea of wave particle duality.
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Section 4: Quantum Mechanics and Atomic Orbitals
CREDITS
The De Broglie equation and Schrödinger's mathematical
treatment of an electron are touched on before quoting the
important consequences of quantum mechanical theory.
An atomic orbital is pictured as an electron probability
diagram or "electron cloud", and this concept is illustrated
graphically comparing a quantum mechanical orbital with a
Bohr orbit.
Producer/Director
Peter Hicks
Sciprt Consultant
Section 5: The Periodic Nature of Electron Configuration of
the Elements
Dr Roy Tasker
The energy levels and their organisation as determined by
solution of the Schrödinger equation for successive electrons
is shown. This matches the layers or jumps in the ionization
energy graph examined earlier in the program and the periodic
table of elements.
Some of the periodic groups arising from the energy levels,
like the alkali metals and the inert gases, are shown together
stressing orbital pictures and the valence shell.
University of Wester Sydney
Teachers Notes
Peter Hicks
Computer Graphics & Animation
Graeme Whittle
Section 6: Hydrogen and Helium - How Do the Gases Reflect
the Electron Configuration of the Atoms?
Students are asked to distinguish between the gases after
having the electron configuration of each atom carefully
described.
Copyright
CLASSROOM VIDEO (1991)
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