Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Quantum tunnelling wikipedia , lookup
Old quantum theory wikipedia , lookup
Atomic nucleus wikipedia , lookup
Double-slit experiment wikipedia , lookup
Photoelectric effect wikipedia , lookup
Quantum electrodynamics wikipedia , lookup
Theoretical and experimental justification for the Schrödinger equation wikipedia , lookup
Page 2 PROGRAM CONTENT Page 3 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. Page 4 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. Page 6 Page 5 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) and Orders: Classroom Video 1/1 Vuko Place Warriewood, NSW, 2102 Ph: (02) 9913 8700 Fax: (02) 9913 8077 email: [email protected] UK: Phone: (01454) 324222 Fax: (01454) 325222 Canada: Phone: (604) 5236677 Fax: (604) 5236688 USA: Phone: 1800 665 4121 Fax: 1800 665 2909 Page 7 Page 8 Page 10 Page 11