Now we move to the “nucleus” of chemistry: matter!
Textbook Reading: Chapter 3, page 55 to top of page 66. We’ll save the Energy part of the chapter for next week.
As we learned in the first lesson, matter is anything that takes up space and has mass. In this chapter, Tro discusses some different ways to classify matter.
1. States of Matter
Even though matter can be found all over the Universe, you only find it in a few forms, called the “states” or sometimes “phases.” The textbook introduces you to three states of matter: solid, liquid and gas (page 57). Did you know that there are other states of matter as well? Now people generally recognize at least five states of matter!
Plasma is widely considered to be the fourth state of matter. What is it? Plasma is a gas in which the atoms are ionized, meaning there are free negatively-charged electrons and positively-charged ions.
This video explains plasma (if the viewer doesn’t work, here’s a direct link).
Hopefully we’ll get to explore more about plasma in the future.
If plasma is super high energy, then Bose-Einstein condensates are the exact opposites. Satyendra Bose and Albert Einstein predicted that matter would change state at temperatures approaching absolute zero way back in the 1920s, but no one was able to verify the existence of these condensates until 1995.
Here, one of the scientists who made a Bose-Einstein condensate explains what they are like (direct link):
Interested in learning more? The Chem4Kids website covers the basics of the five main states of matter in a particularly clear way.
2. Classifying Matter According to Composition
Matter can also be grouped according to what makes it up. If it is a pure substance, it contains only one kind of atom (an element), or molecule with different kinds of atoms (called a compound). In this case, the ratio of atoms in the compound is always the same.
Mixtures contain varying amounts of atoms in a combination of substances. If the mixture is uniform, it is called homogeneous. If you can point to something in the mix and say that substance is different from the rest, then it is called heterogeneous.
Pay particular attention to Figure 3.8 on page 59. We will be going over some concrete examples in class.
3. Chemical and Physical Properties
We will be investigating the physical properties of matter in our laboratory this week. Some physical properties are boiling point, density, and color. We’ll be learning a lot more about chemical properties as we progress through the book.
This video goes over the differences between chemical and physical changes in more detail if you’d like some clarification.
(Direct link if viewer is not working)
4. Law of Conservation of Mass
When French chemist Antione Lavoisier figured out that phylogiston was not part of combustion, he also realized that nothing was being created nor destroyed during chemical reactions. We might not always immediately realize where each substance is going in a reaction, but eventually we can track it down.
Pay particular attention to that tiny sidebar on page 65. We now know the law of conservation of mass is an oversimplification. It works with most chemical reactions, but in some nuclear reactions changes in mass do occur.
That’s it. Not so bad was it?
If you have any questions whatsoever, please leave a comment, send an e-mail or comment to the Yahoo group.