Structural Formulae: how do they know and what does it mean?

[Annie N]

My daughter is studying Apologia Biology, and they are talking about structural formulae.

Rather than go into a lot of detail about what they are trying to teach, what I can't figure out is, how did they figure all this stuff out? I am assured by my daughter that they cannot see this stuff under a microscope... but they talk about chain molecules and ring molecules, and isomers; single, double, and triple bonds, etc.

I am hoping that understanding how they figured it out will help her (and me!) understand the point? essence? of what they are saying.

Thanks very much :D

[Jane in NC]

Rather than go into a lot of detail about what they are trying to teach, what I can't figure out is, how did they figure all this stuff out? I am assured by my daughter that they cannot see this stuff under a microscope... but they talk about chain molecules and ring molecules, and isomers; single, double, and triple bonds, etc.




Hi Annie,

I believe that your question can be restated as this: if one cannot see something like an an atom or a molecule, how did scientists begin to suspect their existence?

While earlier philosophers and scientists had speculated on the existence of the very small, it was Boyle, Dalton and Brown who laid the foundation for atomic theory as it is accepted today. (Boyle was a 17th century scientist while Brown and Dalton worked in the early 19th century.) You can look up on the Internet the large cast of characters who contributed to the body of work that led to modern chemistry. By studying the behavior of certain elements, chemists were able to predict things that should happen. Repeatedly they were correct which led to generalizations, i.e. theory.

Interestingly, technology is now available to "see" molecular images. Two scientists (Rohrer and Binning) won a Nobel Prize for their work on the scanning tunneling microscope which maps surfaces at the atomic level.

I have never heard anyone argue against atomic theory being untrue because it lacks proof from direct observation. Does anyone want to correct me?

Jane

[Myrtle]

Annie,

One of the best science books that I ever read is called "The Magic Furnace." (http://www.amazon.com/Magic-Furnace-Search-Origins-Atoms/dp/0195143051/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1204679153&sr=8-1) It was recommended on this board several years ago by someone as a good, entertaining story about the history of the evidence that revealed atoms. And it was awesome.

Your library will probably have it and once you get into this book you won't put it down.

[Tina in Ouray]

I've already ordered a copy!

Tina in Ouray, CO