CHEMISTRY CHAPTER ZERO

Homework Assigment about Atoms

It has been a pleasant dinner party, and the conversation has flowed over many interesting topics. As expected, your guests preferred your grape salad over the jello salad. You, of course, acknowledged that you are a chemist (and brought shudders from your companions) and complained about the rigors of your PChem course.

There was a bit of a break in the conversation, and in that quiet moment, Sylvia, a mechanical engineer, spoke, “You know, I was told about atoms, but I can’t see them. Why should I try to think about atoms the way you do?”. Alan, a hydrologist, picked up the theme. “Just what is an atom anyway? I do all sorts of technical calculations, but they involve gallons and acre-feet and stuff; I never have to worry about atoms. What is the evidence for atoms?” The young air force captain across the table looked thoughtful and said “I command a radar maintenance unit, I’m an expert with electronics, and for the life of me, outside of what I was told as the truth in high school, and that was all that Dalton's Law stuff, I can’t see why I should believe in atoms.”

The party broke up amicably, but knowing that this fun group would meet again next week, you resolved to be ready next time and to present them with really good experimental evidence for the existence of atoms. You went to your dictionary and found that an atom is defined as “the smallest particle of an element that can exist either alone or in combination”. “Lousy starting point”, you grunted, “I need a much better definition of an atom if I am going to make clear arguments to my friends on Friday night.”

Assignment :

Define what chemists (should) really mean by the word “atom”, provide summaries of experimental evidence originating after 1900 (and not including Dalton's Law arguments), and explain why these arguments should convince people like your dinner companions, who have good technical training (but who are not chemists).

You may do this assignment in one of two ways:

You and your team members present a 5 minute skit in class next time.

In carrying out this assignment, be sure to distinguish between a definition of an atom and a description of the properties of atoms. I will certainly make the distinction when I grade your work.

Late work will receive a grade of zero. (Remember, this has to be done before the next dinner party!)