Atomic Structure and Elemental Properties:

Relating the Movement of Electrons with the Emission of Light


Gregory D. Fisher

New Milford High School

New Milford, CT

Project: HS0551, Astrochemistry: The evolution of organic molecules in interstellar clouds: Using MO theory to model new molecules and reactions between stars

Mentor: Y.E. Rhodes, Chemistry Department,  New York University


August 17, 1998


Grateful Acknowledgment to:

Camille and Henry Dreyfus Foundation & Research Corporation

Dr. Samuel Silverstein and Mr. Jay Dubner, Columbia University

Overview of Activities

The first activity in this unit applies simple graphing of atomic radius (size) versus atomic number across a row/period (elements #3 through #10) and down a column (Group 1A). [Content Standard Unifying Concepts- Systems, order, and organization] Following this activity, students will be presented with a problem that seemingly contradicts their experience: increasing the number of "things" in a box (i.e., electrons in the atom), results in a decreasing atomic size (across a row). The purpose of this problem is to elicit student inquiry. [Content Standard A - Abilities necessary to do scientific inquiry]

To answer this seeming discrepancy, students will construct a magnet-model of the atom. [Content Standard Unifying Concepts- Evidence, models, and explanation] This is the first concrete representation of electron orbitals to which the students are presented. This second activity will be followed by flame tests of several elements and, then, spectroscopic analysis of elemental light sources - in a lesson designed to apply the model construction with actual chemical phenomenon. Light sources (e.g., sun and incandescent light) will then be investigated to determine the elements producing the light. The lesson will conclude with a video showing different fireworks and a discussion of the elements involved in the specific colors displayed.

Experimental chemistry unit plan

Atomic Structure Atomic Structure and Element Properties

Purpose: To explain selected elemental properties by investigating atomic structure.

SWBAT: 1. describe the relationship between atomic size and atomic number as one goes across (period) or down (family or group) the periodic table

2. explain why atomic radius decreases in a period although the number of electrons and protons increases [Content Standard B - Structure of atoms]

3. using spectroscopic analysis, identify the element(s) in a light source [Content Standard B- Matter/Energy interactions]

4. identify an element by flame test

5. explain how fire works give off distinctive colors

[Teaching Standard A- Select content and adapt curricula]

Activities: 1. graph atomic radius v. atomic number by group (Group1) and period (elements #3-10)

2. construct ring magnet-model of Bohr atom

3. spectroscopic analysis of light sources

4. elemental flame test

5. view/discuss video showing fireworks

Resources: 1. graphing supplies

2. magnetic model

3. spectroscope and light sources

4. lab: flame test

5. video showing fireworks

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