So. We’re a couple of weeks into our journey of discovery. I hope that you are getting something out of these articles, even if it’s just the realization that you already know a lot more science than you think you do. Please let me hear from you with your comments and questions. It’s a whole lot more fun answering questions than thinking up topics on my own.
We started off by setting the stage and establishing the really remarkable scope and scale of science. Last week, we got a little bit into matter and how matter relates to gravity and inertia and how everybody already pretty much gets how mass, gravity and inertia influence everyday things like a moving car or a ball thrown in the air. Today, we continue our exploration into all the “stuff” that makes up everything in the universe.
National Center for Biotechnology Information (2024). Periodic Table of Elements. Retrieved May 28, 2024 from https://pubchem.ncbi.nlm.nih.gov/periodic-table/.
If you’ve ever had a science class, particularly a chemistry class, you’ve probably seen the Periodic Table of the Elements. It was that figure with all the boxes, with the letters and numbers inside—probably inside the front cover of the book. If you never got very far into chemistry, chances are that you never got very deep into the Periodic Table, which is a real shame, because, despite its orderly and fairly simple-looking appearance, the development of the Periodic Table is one of the great intellectual achievements in history. I love some history with my science, so if anyone is interested in the story of the people and events that make up the process of science, let me know and we can go down that road from time to time. There are some REALLY important people, whose work has literally made billions of lives possible, that almost no one has heard of. But I digress. Back to the Periodic Table.
The Periodic Table is a listing of all of the different elements that make up everything that exists in the universe. “Elements” are types of matter that are composed of only one thing, and they can’t be reduced to any other constituent parts. Iron, for instance, is an element. You can take a bar of iron and (theoretically) you could cut it in half, then cut the halves in half, and so on, until you got down to the very tiniest piece of iron imaginable. That would be an iron atom. Steel, on the other hand, is not an element, it is a compound, which is something composed of more than one type of element. Steel is made of iron, combined with carbon, oxygen and usually some other metallic elements, like chromium, as well. We can go into atoms and suchlike another time. Anyway, iron is an element, as is oxygen, hydrogen, uranium and carbon. One of the amazing things is that everything in the universe is made up of one, or a combination of, only 92 different elements. Even more amazing is that over 98% of ALL of the matter in the entire universe is composed of only two of those 92 elements—hydrogen and helium, the two lightest, simplest elements there are. Seventy-four percent (by mass) of everything that is, is just hydrogen. That leaves 24% helium and just 2% of the matter in the universe contains any of the other 90 elements. Considering how much hydrogen there is in the universe, you would think that there would be much more hydrogen on Earth than there is. Hydrogen only makes up less than 1% (by mass) of the Earth. Helium is much less than that. The Earth, by mass, is mostly iron (about 32%), followed by oxygen (about 30%), silicon, magnesium, sulfur, nickel, calcium, aluminum and traces of all the other elements. You, and every other living thing, are made up of still another combination of elements. Living things are mostly (99%) composed of only 6 elements: carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. I’ve always been fascinated by the fact that you can take the same 6 elements that make up most of a person and combine them in a different way and get what is basically gunpowder. As any good cook will tell you, it’s not the ingredients that make the difference—it’s how you put them together.
How and why these elements came to be distributed as they are is really the story science has to tell. Think about that the next time you look up at the night sky. Instead of thinking about how pretty it is or any of that stuff, what you should really be thinking is “Wow! That’s a lot of hydrogen and helium.” Perhaps it’s not very romantic, but it’s something fun to think about. Actually, over 99.999999 percent of what you see when you look up in just empty space and most of the matter is located here and there (like in stars, planets, nebulas and black holes), but that, too, is a subject for another day. And again, not romantic.
By the way, if you click on the link in the citation under the Periodic Table image, it will take you to the web site of the National Institutes of Health with an interactive version of the table where you can explore in more detail. Ain’t technology wonderful?
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