Everything that is, is matter. We touched on this a bit before, but I think we need to hang some more meat on those bones before we go much further into our scientific journey. Understanding, like science itself, needs to build up from a firm foundation in basic principles. The simple definition is that matter is anything that takes up space and has mass. Taking up space is a simple enough concept, but mass is trickier. If you’ll remember from one of our earlier articles, we touched a bit on the difference between the mass of something and the weight of something. “Mass” is how much matter is contained withing an object and he mass of an object is a constant, no matter where it is—on Earth, on the Moon, or in deep space. Mass (how much “stuff” is in a thing) really can’t be measured directly by any normal mechanism. “Weight”, however, can be used as sort of a substitute for mass, and it’s is easy to measure. All you need is a scale, which will measure the force of gravity exerted on a given mass, so “weight” is relative to a given gravitational field, which is why a baseball weighs less on the Moon than it does on Earth—the Moon has less mass than the Earth, so it exerts less gravity. We’ll talk more about gravity down the road. Since we are Earthlings, we generally measure mass relative to Earth’s gravity, so we assign the baseball a mass of about 145 grams. That’s about 5 ounces, using the incredibly silly Imperial measuring system, instead of something simple, like the metric system.
But what is matter made of? There’s a simple answer to that. Matter is made of atoms. There are also more complicated answers, because atoms are, themselves, made up of smaller subunits, called protons, neutrons and electrons. Atoms can also combine with other atoms to form larger structures, called molecules. We touched on molecules just a bit in our discussion of Nitrogen. If you want to get REALLY out in the weeds, the protons and neutrons in an atom are actually composed of even smaller parts (ever heard of a “quark”?). You’ve probably heard of a photon, which is usually thought of in terms of light. Maybe you heard in the news a few years ago about the Higgs boson when it was finally observed at the Large Hadron Collider at CERN (the European Organization for Nuclear Research). The Large Hadron Collider is the most powerful particle accelerator, or “atom smasher”, in the world. “Hadrons”, by the way, are just a category of subatomic particles. Protons and neutrons are hadrons, so the LHC basically smashes protons together to study the even smaller subunits that they are made of. The LHC is a giant machine inside a circular tunnel 27 kilometers (about 17 miles) long, bored through the granite under the Alps between France and Switzerland. It took about 10 years to build at a cost of about $4.75 billion dollars. The LHC has generated a lot of new scientific knowledge about how the universe was made and why things work as they do, but the main goal of the LHC was to observe a particular subatomic particle called the “Higgs boson”, which is important because the Higgs boson is what causes matter to have mass. The Higgs boson was finally observed in the LHC in 2012. It was a very big deal, but that’s about all I’m going to say about bosons, because that’s pretty much all I know about bosons. I’m certainly not an authority on particle physics and I don’t think a deep understanding of bosons is really part of the scientific literacy we’re aiming to build up in these articles.
We do need to understand the basics about protons, neutrons and electrons, though, because that’s what the universe is made of. We’ll dip a toe into discussing photons when we get around to discussing light and electromagnetism, but we’ll stick with protons, neutrons and electrons, for now. All atoms are made of those three particles, and nothing else. Furthermore, all protons are the same, and the same goes for neutrons and electrons. A proton, neutron or electron in an iron atom is exactly the same as one in an atom of helium. What makes iron, iron and helium, helium is the numbers of protons, neutron and electrons in the atom. Helium has 2 protons, 2 neutrons and 2 electrons. Iron has 26 protons, 30 neutrons and 26 electrons. Anything with 2 protons HAS to be helium and anything with 26 protons HAS to be iron. So, there are three primary particles which compose all matter. Doesn’t it seem like there should be more than that? Everything in the entire universe is just variations of groups of protons, neutrons and electrons.
Source: Freepik (freepik.com)
But it gets even more amazing when you consider that there are only a relative few different types of atoms that make up everything. For most of my life, there were 92 “naturally-occurring” elements. An element is a basic unit of matter, like iron, oxygen, or magnesium, that can’t be broken down into something simpler. The identity of each element is determined by the number of protons in the atom, like we mentioned. Hydrogen is an element. Each hydrogen atom has 1 proton. Carbon is an element and each carbon atom has 12 protons, and so on. Hydrogen is the smallest, simplest and lightest element with 1 proton and 1 electron. It used to be thought that Uranium, with 92 protons, 146 neutrons and 92 electrons, was the largest and heaviest, naturally-occuring element. Then physicists started experimenting with particle accelerators, back around 1930. They were able to smash particles together to create new atoms, not found in nature. As of now, there have been an additional 26 elements created experimentally, for a total of 118. Most of the new ones only exist for a very, very short time because they are unstable.
Now, recall that I mentioned that there are 92 naturally-occurring elements listed on the periodic table, from hydrogen to uranium. It turns out that there may only be 91, because one of the 92, Technetium, with 43 protons, may not actually occur naturally. We use a lot of it for radiation therapy, but it’s all synthesized in laboratories. Even though there are 92 natural (or 91) elements, most of the periodic tables I ever saw listed at least 105 elements. The four newest ones, up to 118, were discovered fairly recently and were added to the periodic table in 2016. It turns out that there may actually be traces of some of these “new” elements that are actually found in nature, so the number of “naturally-occurring” elements may be 98. Ish.
Let’s sum up atoms a bit. All matter is made of atoms and atoms are made of three subatomic particles: protons, neutrons and electrons. The number of protons in an atom determines what kind of atom (or element) it is. Everything in the universe is made up of some combination of 92 different elements, as far as we know, but we’ve created several new, unstable atoms in particle accelerators and some of those might exist naturally somewhere else in the universe.
But what about all the stuff that isn’t hydrogen, or iron, or magnesium. There are infinitely more than 92 different things in the universe. What about daisies and hot dogs and grass? They aren’t elements. They aren’t listed on the periodic table. Similar to how atoms are made up of protons, neutrons and electrons, most things are made up of more complex structures called molecules.
Source: Freepik (freepik.com
Molecules are made of atoms that are bound together. We already mentioned one simple molecule, N2, in our articles on nitrogen. N2 is two nitrogen atoms bound together, and that N2 molecule is how almost all nitrogen is found here on Earth. Atomic nitrogen (single nitrogen atoms) is very rare and almost instantly combine with other atoms whenever they are formed, as when the energy of a lightning bolt splits an N2 molecule apart. There are also extremely complex molecules, mostly found in living things, like proteins, some of which are composed of thousands of atoms of various elements, like carbon, nitrogen, oxygen, hydrogen and sulfur.
While there are only 92 (-ish) naturally-occurring elements, they can combine into an almost infinite variety of molecules, and that is where all incredible diversity of “stuff” comes from in our universe. How atoms go about combining into molecules is a story unto itself, so we’ll tackle that in another article, or two. Today, however, you may have a little better idea of what the universe is made of.