The story of how science came to understand what we’re made of really began with “the Father of Chemistry,” French nobleman Antoine-Laurent Lavoisier. Before he lost his head to the guillotine during the French Revolution, Lavoisier recognized that stuff came in two varieties: that which could be broken down into simpler stuff (compounds) and that which couldn’t (elements, as in elementary). This simple-yet-momentous observation prepared the groundwork for the science of chemistry.
Ten years later, in 1803, English scientist John Dalton quantified Lavoisier’s insight. Reviving the ancient Greek term for indivisible atoms (a-tom, that which can’t be cut), Dalton’s genius was to suggest that what distinguishes the properties of one element from another depends on the mass of each of its constituent atoms; and that compounds are formed by a combination of elements in simple whole-number ratios (e.g. two atoms of hydrogen combine with one atom of oxygen to make water).
We now know that (1) an atom is composed of light, negatively charged electrons surrounding a heavy, dense nucleus consisting of positively charged protons and neutral neutrinos; and (2) one element is principally distinguished from another by the number of protons in its nucleus.
Recall the Periodic Table on the wall of your school science lab? Dalton’s successor, Russian chemist Dmitri Mendeleev, invented this ingenious way of arranging elements according to weight (left to right) and properties (top to bottom). So for instance: The lightest element, hydrogen, atomic number 1 (whose nucleus contains just one proton) is upper left; organic compounds all contain carbon, atomic number 6 (six protons in each nucleus); uranium, atomic number 92, is the heaviest naturally occurring element.
The beauty of the periodic table is its universality: Everything (everything!) you touch, see, smell and taste consists of either pure elements or, more likely, a mixture of the elements found in this deceptively simple matrix. Take your body. It’s made up of about 65 percent oxygen, 18 percent carbon, 10 percent hydrogen and 3 percent nitrogen by mass, while the remaining 4 percent consists of traces of almost every other naturally occurring element in the table.
Since the time of Lavoisier, Dalton and Mendeleev, chemists, physicists and astronomers have made huge strides in understanding the origin of elements. Thirteen-plus billion years ago, soon after the creation event we term the Big Bang, the universe consisted only of the lightest elements hydrogen, helium and lithium (one, two and three protons, respectively). No carbon, no oxygen, no zinc, no iron, no uranium: These had to be synthesized from the original three elements. How? By nuclear fusion. Where? Inside stars. So many technical problems had to be solved in order to arrive at a complete understanding, that detailed answers have only been available in the last 50 years. And the biggest hurdle investigators had to overcome is right here in your blood: iron.
Next week: Forging the elements.
Barry Evans (barryevans9@yahoo.com) recommends Tom Lehrer’s The Elements for anyone wanting a quick brush-up. Son of Field Notes (a compilation of Barry’s columns for the last 18 months) is for sale at Eureka Books and Northtown Books.
This article appears in Mainstay Unraveled.
Several sharp-eyed readers noted that I said the nucleus of an atom is composed of protons and neutrinos. I should, of course, have said protons and NEUTRONS.
Groovy.
Points to note;
*Atoms are not made of light. In an excited state (when space collides! More like, when matter (or pressure or energy) collides) the electrons within atoms jump around. When they drop down from their more excited state, they release that energy in the form of photons. Photons as in “photo’ as in “light.” (…which is both a particulate AND a wave. omgosh fun!) Light emission was one of the earliest methods of figuring out which element was which as each element creates a different pattern. It’s the method currently used for trying to figure out what distant, celestial objects are made of. Hydrogen has the honor of being the first pattern recognized. It’s also what I blame for any question involving Planck’s constant. grrrr. (a note for that note: trying to make things as easy to visualize as possible. Think I even see one spot that could be corrected in my ramble. Electrons gain/lose electricity to other electrons, not really so much to matter though in a way; the term “matter” works because it’s atoms which are getting jiggy with each other and swapping material that makes all the above happen but no, because electrons are technically less than matter since they have insignificant mass. La la la.)
*Mendeleev was not the only one attempting to organize the periodic table when it was defined. Yes, his is definitely the most similar to the one seen today. (Many changes have been made. Just a couple rows here and there. It was pretty decent considering he made space for elements that weren’t known during his time.) The (super amazing) thing about the periodic table is that it’s just a method of categorizing. (Kinda like a sock drawer. It doesn’t HAVE to be organized by color. It can be organized by length or fabric.) It’s current model is a great one, though it can be rearranged and recreated using various other properties in order to make some funky looking models. Or more simple ones. Or whatever ones! It’s like origami, with less paper and more idea.
I like where I think you’re going with this series. The next bit is always one of my favorite parts of the tale. It involves lots of KABOOM and change. (change x.x Almost said the horrid “e” word. Can’t have that :p) Some implosions too. Man, it’s awesome. tries to be patient for the next article and not ruin it
To Talvi. I think you misread the sentence:
” . . .an atom is composed of light, negatively charged electrons surrounding a heavy, dense nucleus . . .” Not ‘light’ as in the electromagnetic phenomenon, bur rather ‘light’ in terms of mass, as in lightweight electrons. But wait. That might be construed to mean ‘the weight of light’.
Totally did misread that one! Note to self: pay attention to commas and sentence structure.
I read something, many years ago, about the mass of the internet not including hardware components. It was really interesting and am sure could be used as a touchpoint for any arguments on light having weight.
The weight of light! How cheeky. Try that again on April Fools’ day and then argue that “technically it’s not a joke.” Watch every physics lover in Humboldt devolve into a mass of debate and frustration or just sit back and chuckle because there is no way anyone who could explain it really has the time to explain it. (I presume they’d be too busy building living spaceships to putz around the galaxy or else writing articles to boggle Humboldt’s collective mind (Or the minds of the birds whose cages the NCJ lines).)