Introduction to Chemistry
Getting Started
So you think you hate chemistry, huh?
Well, I love it, in large part because it makes so many things in my life more interesting and understandable. I'm hoping I can help you to feel the same way.
Class Pages (like this one)
Each class page will appear a few days before the upcoming class. After each class, I might add more material so you can follow up on subjects that pique your interest. So it is a good idea to look at each class page both before and after class.
Ongoing Assignment: Chemistry Everywhere
Ask questions. If you are curious about something chemical in the world around you, please let me know, by stating your question in the form at the bottom of this and every course page. I'll try to include it at an appropriate time in the course. Chemicals and chemical processes are all around you: in the kitchen, the garden, and the garage; in the medicine cabinet and the cleaning closet; in your car's gas tank, engine, and exhaust; in lights, solar collectors, and all kinds of electronic devices; in your body; and all over the night sky. If you want to understand your world better, look for things chemical and ask me about them.
So you think you hate chemistry, huh?
Well, I love it, in large part because it makes so many things in my life more interesting and understandable. I'm hoping I can help you to feel the same way.
Each class page will appear a few days before the upcoming class. After each class, I might add more material so you can follow up on subjects that pique your interest. So it is a good idea to look at each class page both before and after class.
Ongoing Assignment: Chemistry Everywhere
Ask questions. If you are curious about something chemical in the world around you, please let me know, by stating your question in the form at the bottom of this and every course page. I'll try to include it at an appropriate time in the course. Chemicals and chemical processes are all around you: in the kitchen, the garden, and the garage; in the medicine cabinet and the cleaning closet; in your car's gas tank, engine, and exhaust; in lights, solar collectors, and all kinds of electronic devices; in your body; and all over the night sky. If you want to understand your world better, look for things chemical and ask me about them.
An acquaintance said that in choosing foods and remedies, they try to avoid chemicals. Got news for them, and for all of us: this person and you and I ARE chemicals, nothing but chemicals. Every bit of ordinary matter in the universe is all chemicals. Any idea what distinction this person is trying to make?
Preparing for Class
New terms and ideas for the first class
It is inevitable that our first class will include many terms that are new to you, especially if you have not studied chemistry before or for a long time. To learn more about each subject, look it up at Wikipedia, where the introductory paragraph or two on the subject will usually be all you need to read in order to help you with this class. But if you want to know more, Wikipedia can also take you very deeply into each subject. Many Wikipedia entries start with the simple, and progress to the more complex, so read as far as the material makes sense to you.
New terms and ideas for the first class
It is inevitable that our first class will include many terms that are new to you, especially if you have not studied chemistry before or for a long time. To learn more about each subject, look it up at Wikipedia, where the introductory paragraph or two on the subject will usually be all you need to read in order to help you with this class. But if you want to know more, Wikipedia can also take you very deeply into each subject. Many Wikipedia entries start with the simple, and progress to the more complex, so read as far as the material makes sense to you.
• matter
• chemical substance (also called pure substance)
• mixtures, homogeneous and heterogeneous
• atom and element (why pair these words?)
• molecule and compound (why pair these words?)
• phases of matter: solid, liquid, gas
• science -- Do you know what science is?
• chemical substance (also called pure substance)
• mixtures, homogeneous and heterogeneous
• atom and element (why pair these words?)
• molecule and compound (why pair these words?)
• phases of matter: solid, liquid, gas
• science -- Do you know what science is?
Read these pages and watch any videos they provide:
Questions to Think About
• Do you know why it's called a cloud chamber?
• In the cloud-chamber video, can you spot any clouds that do not appear to come from the rod?
• What is an element? What is a compound?
• What three forms -- or phases -- of water do you encounter frequently?
• In your kitchen, look for examples of pure substances. Look for examples of homogeneous mixtures and heterogeneous mixtures.
More Resources (optional)
• Where Do Elements Come From? The answers might surprise you.
Don't let this video scare you away. If you truly have little or no background in chemistry, this video will be quite challenging. Just try to get the gist of it, but don't worry about the details. Some of these concepts will come up later in the course in contexts that will make them fit it with other things you have learned by then. The short answer to the question Where Do Elements Come From? is that most of them were made in previous generations of stars that preceded our Sun. And all of those elements account for only 2% of the contents of the universe. The other 98%, almost all we see in the night sky, is the hydrogen and helium that was produced at the beginning of the universe, 13.8 billion years ago.
Click to enlarge.
• Cloud Chambers: Click HERE to learn more from Wikipedia about cloud chambers.
For a source of radioactivity, the author of the video above used a welding rod made of tungsten mixed with 2% thorium (element 90). Thorium isotope 292 decays by loss of an alpha particle (2 protons and 2 neutrons, same thing as a helium nucleus), producing radium 228 (element 88). Radium decays further into radioactive products until finally, a decay produces lead 208, which is stable. The amount of radioactivity is very small, so these rods are not considered harmful enough to require licensing, which is required for distributing highly radioactive materials. So, like everything, available at Amazon.
Did you spot any clouds that did not appear to have come from the rod? These might be the result of external radioactive sources in the lab, or even of particles resulting from cosmic rays, which collide with air molecules and create showers of energetic particles in our atmosphere.
This spectacular chamber contains the same type of thorium rod that I use in a small, inexpensive cloud chamber I have at home (picture below). Compared to my little chamber, this one is the video is larger, colder, and better lighted. You can see how many more tracks are visible under the best conditions. Someone asked how far the tracks travel; the answer is much farther than the chamber allows us to see. Notice that many tracks are thicker at their far end. Collisions of alpha particles with molecules in the atmosphere inside the chamber slow the alphas down, allowing them to affect the air, water, and alcohol molecules more strongly, thus producing denser clouds.
Try this at home? A faint track is visible moving downward from near the tip of the rod.
Click to enlarge and improve contrast.
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Other recommended reading
Poem: The Abacus and the Rose
In this poem, what is "the spring"?
Is there more than one sensible answer to this question?
What do I mean by "sensible"?
