Electrons and Quantum Mechanics - Oakland Schools

Electrons & Quantum Mechanics
Activity #1 - Locating an “s” Electron in an Atom by Analogy
Questions to be investigated
How is an electron cloud formed?
What is the probability that an electron will be found in a particular region or space of
an atom?
How is the radius of an atom determined?
Objectives
Students will get insight into the meaning of abstract concepts and terms (orbitals,
electron density, charge cloud, probability graphs, etc.) associated with the wavemechanical
model of an atom.
Students will determine the distribution of impacts of marble drops around the bulls eye
of a target.
Students will obtain and interpret probability information on the distribution of marble
drops around a bulls-eye of a target.
Teacher Notes
Expected Student Background
Students should review wave-mechanical model of the atom.
Pre-Laboratory Discussion
The materials and procedures of the activity may be illustrated during a brief prelaboratory
discussion. During this discussion, explain that the activity’s purpose is to
develop “experimentally” a “charge cloud” diagram and probability graph. Point out the
analogy to comparable mathematically derived electric charge-cloud diagrams and
probability graphs found in some student texts.
NOTE: Student graphs should begin at a radius of 0, where the probability of finding an
electron is 0.
Teacher-Student Interaction
1. Be sure the marbles are caught after their first bounce.
2. Be sure marbles are dropped from a consistent height (2 m).
3. Ask students whether they expect each group to get the same pattern (the patterns
should be similar, but not identical).
4. Do students expect a marble to land exactly in the middle?
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