In my experience browsing through chemistry textbooks, authors tend to focus on different things when introducing chemistry in the first chapter or so. Thus, after careful examination of a number of textbooks, I thought it most suitable to further our study of chemistry by discussing the properties of matter. Although it might seem elementary, and you might be waiting for the more difficult stuff, bear with me on this one. I browsed through some MCAT review books and practice exams recently and there are indeed questions on the MCAT about seemingly trivial things like the scientific method, induction, and hypotheses. I'll be sure to start posting some MCAT questions on the site very soon after we cover a few more topics, so just stay tuned for that.
On to properties of matter. When I first defined chemistry in the introduction post, I provided a simple definition of chemistry, summed up and simplified from a number of textbooks, that was merely the study of matter. Well, yes, that definition is somewhat oversimplified, but that's why I'll be delving deeper into it today, specifically with a breakdown of what matter really is. You may certainly have some general idea of what matter is; it has been a word repeated throughout science classes even in elementary school. When you think of matter, the first thing that should follow is mass. This is because matter is defined as anything that (1) occupies space and (2) exhibits the properties of mass and inertia (Petrucci et al. 2010). And because it is equally important to know, mass is defined as the quantity of matter in an object (Ebbing and Gammon 2009).
It is important to know that matter consists not just of the things that are the most obviously tangible to us, such as our cars and our houses, but also things that exist that are often times a little more difficult to perceive, such as gases within our atmosphere. Indeed, these gases occupy space and have the property of mass (Petrucci et al. 2010).
Because chemistry is the study of matter and thus deals with its composition, it is helpful to know that composition is defined as the constituents of a sample of matter, in addition to their relative proportions. Let's give an example that we are all familiar with: H2O. Water is composed of two parts hydrogen and one part oxygen, and by mass, water is composed of 88.81% oxygen and just 11.19% hydrogen. Other hydrogen-and-oxygen-containing compounds have a different composition, such as hydrogen peroxide, which has a higher composition of oxygen and a lower composition of hydrogen than does water (Petrucci et al. 2010). In my next post that is the second part to this post, I will cover a related topic, physical and chemical properties of matter.
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