Mufasa: Everything you see exists together in a delicate balance. As king, you need to understand that balance and respect all the creatures, from the crawling ant to the leaping antelope. Simba: But, Dad, don’t we eat the antelope? Mufasa: Yes, Simba, but let me explain. When we die, our bodies become the grass, and the antelope eat the grass. And so we are all connected in the great Circle of Life.
(Hey, who else is nostalgically hyped for the Lion King?)
Obviously, actual ecosystems don’t work that way. In Mufasa’s circle, if one of the nodes disappears due to a mysterious antelope-plague, all of life would break down. But more likely, the lion would eat a zebra instead. And if there is no grass, the herbivore will eat some leaves of a tree. (Okay, I know that Scar then went ahead to mismanage everything and life did basically die, but there’s also the part where the little plant breaks through showing that life finds a way.)
Ecosystems are intricate webs where everything is connected to everything. If one thing falls away, the balance probably shifts, but it wouldn’t be a full-blown mass extinction. Even if all bees disappear, we’d end up being okay.
We don’t fully understand the intricacies of the ecosystem. We’ve tried, for example through the Biosphere 2 project (planet Earth was considered number 1). This artificial earth was built in the late ’80s in the middle of the desert in Arizona. The “bubble in the desert” was intended as a testing facility, creating a “closed system” where nothing would come in or go out, recreating different natural biomes on a smaller scale to test if a small little earth with human interference would be sustainable.
One of the goals of this facility was to see how we would build human habitats in space, and whether such closed ecological could be maintained. Remember how in the Martian, Watney had to do crazy science to be able to grow potatoes (which is “kind of really possible”, apparently)?
We wanted to recreate a complete ecosystem and failed. Biosphere 2 is on the list of the 100 worst ideas of the 20th century. We obviously do not understand complete ecosystems enough to create an artificial one. It should be noted, though, that the crew members, who spent the full 2 years in the sphere, call the experiment a success.
I am currently watching The Expanse, and in one of the episodes, they talk about the Cascade. This describes how one element in a closed system breaking down (in this case an agricultural biosphere on one of Jupiter’s moons) leads to the whole system will fail in a cascade of events we cannot predict. Cut out the lions at the top of the food chain, and the antelopes will overgraze the grass and everything will die.
We can try to recreate a tiny world, completely isolated from everything else, but do we really know enough to make it work? It’s not a circle of life, life’s an intricate mumble jumble of wiggly squiggly connections and wow I just sound like the doctor talking about time.
Inspiration for this post was an article in ARCADE 37.1 by Nicole DeNamur: Recognizing our environmental arrogance: what an artificial earth taught me about failure
There are two identical twins. One of them travels through space in a high-speed rocket. When they return home, the Earth-bound twin has aged more. This is a result of special relativity. Very briefly, this is due to time slowing down as higher speeds are reached, and why Matthew McConaughey returned to Earth only to find his 90-something year old daughter on her dying bed.
This thought experiment has long been exactly that, a though experiment. But recently, we actually were able to learn what happens to twins when one is in space (granted, not in a high-speed rocket, but on the ISS) for almost a year, while the other twin stays on Earth.
Real Space Twinsies
On March 27 2015, astronaut Scott Kelly arrived at the International Space Station (ISS), while his brother, astronaut Mark Kelly, remained on Earth. (One can have a discussion on who was the luckier of the two.) They did the same activities, ate the same things, and followed the same schedule*, the only difference being that Scott was 400 km from the Earth’s surface, travelling at a speed of 7.66 km/s, while Mark was 0 km from the Earth surface, travelling at a speed of merely 460 m/second, as we all are.
340 days later, March 1 2016, Scott returned to Earth. For the full duration of his time on the ISS, as well as after his return, numerous samples were collected and tests were conducted to monitor his health and compare the physiological and biological changes that happened as a consequence of spacelife. Using his twin brother, a perfect genetic duplicate, as a control.
The effects of space
There are many “unusual” aspects about living in space, compared to living on Earth, including the odd noises of the ISS, the isolation (Scott was in contact with a mere 12 people during those 340 days), the ultra-controlled environment, a disruption of the normal body clock (imagine perpetually being jet-lagged because of constant switching of time zones), living in microgravity and the excess of radiation.
An ultra-combined effort, i.e. a major collaboration between a lot of different labs that looked at all possible aspects of physiological and biological function, the effects of 340 days in space (in this specific set of twins) was published last month. There are a lot of changes that occur to the human body in space, some more severe than others.
There are some changes that don’t really matter much, like changes in the gastrointestinal microbiome and changes in biomass, which were affected during Scott’s time in space, but rapidly returned to normal after he returned. Not much to worry about.
Mid-level risks included known effects of living in microgravity such changes in bone density (you don’t really need to use your skeletal muscles while floating around) and changes in how the heart pumps around blood (you don’t need to fight gravity to pump blood to the head). NASA already knows this and therefore has a rigorous rehabilitation program for returning astronauts to re-acclimatize to Earth’s gravity.
However, it’s the high-risk findings that we all have to worry about, which a mostly due to prolonged floating and prolonged radiation exposure. Due to changes in air pressure as well as that thing I mentioned about blood pumping, a lot of astronauts experience ocular issues after their return, a risk that only increases with increased dwell time off-Earth. This can severely compromise vision. There is also evidence of some cognitive decline. Both those aspects are worrying in the light of long term space travel, we would hope that space-explorers can see and think clearly while carrying out dangerous tasks in dangerous conditions. And that’s without considering a final severe risk…
Who’s the oldest twin?
In addition, the radiation that Scott experienced on ISS is pretty much equivalent to 50 years of normal exposure on Earth. This causes significant genomic instability and DNA damage, and consequentially an increased risk of developing cancer.
One example of this genomic instability has to do with telomeres**. Telomeres are bits of DNA that cap the end of chromosomes. Every time a cell divides, and in the process duplicates its whole DNA library, the telomeres get shorter. When they get too short, the cell can no longer divide. This is something that happens naturally during aging: shortening of telomeres phases out cells until they can no longer divide. Eventually, this leads to cell death.
1 year of space had an odd effect on Scott’s telomeres. Some of them grew longer, while others showed shortening. However, the lengthened telomere returned to normal after Scott’s landing on Earth, while the shortening persisted. So even though Scott was the space twin in our paradox, he seems to have ended up aging faster than Mark…
A lot happens to a body in space
Overall, the results are pretty surprising, prolonged living in space had more of an effect on the human body than researchers expected. And there is probably a lot more to learn, even just with the data collected from Scott and Mark.
On one hand, the twin study showed how resilient and robust the human body is. 91.3% of Scott’s gene expression levels returned to his baseline level within six months of landing, and some of the changes that occurred to his DNA and microbiome were no different than what occurs in high-stress situations on Earth. That’s amazing, the human body has not evolved to survive in space, but it seems to do pretty well considering how outlandish the conditions are!
On the other hand, the prolonged exposure to microgravity and high radiation does have severe effects on human health, leading to increased risk for compromised vision, cardiovascular disease, and cancer development. Even with the rigorous preparation and rehabilitation programs, astronauts go through before and after spaceflight, some of these effects will be impossible to avoid.
The massive study, combining the effort of 84 researchers in 12 different universities is a feat of collaboration (though nothing compared to the black hole telescope, if I’m honest) and it’s definitely a first that the genomes of space vs. Earth could be compared with a true genetic control. This compiled study, and the many pieces of research that are expected to be published in the next year with the results from the individual studies provide crucial insight on the effects of space in the long term. If we think that it takes approximately 1 year for a return journey to Mars, this research is valuable for the health of future astronauts and mankind’s ambition to explore further into space.
Want to know more? Watch NASA’s video on the three key findings, or read more in the Science paper or the NASA website (links below).
Sources:
Markus Löbrich and Penny A. Jeggo. Hazards of human spaceflight. Science 364 (6436) p. 127-128. 2019. DOI: 10.1126/science.aaw7086
Francine E. Garrett-Bakelman, et al.The NASA Twins Study: A multidimensional analysis of a year-long human spaceflight. Science 364 (6436) eaau8650. 2019. DOI: 10.1126/science.aau8650
Cover image: The International Space Station crosses the terminator above the Gulf of Guinea, image credit NASA
*I remember reading this somewhere, but I cannot find the source anymore. It is thus possible that Mark just went about his normal life. Regardless, it is amazing that NASA had the opportunity to do this experiment with a perfect genetic control.
** Fun fact, my spelling check does not know the word “telomeres” and suggests that I mean “omelettes”. Well, I guess they both get super scrambled up in space? (Eeeeh for an inaccurate joke, sorry).
It goes without saying that 3D printing is cool*. The ability to think up any three dimensional structure, design it in a 3D design software and have it materialize blows my mind. Granted, I’m making it sound like it’s a very easy and fast process and I know that’s often not the case, but I also know that for a lot of engineering and physics laboratories, the ability to relatively quickly print a model or prototype for anything is extremely useful. In addition, it’s an amazing educational resource. You can print model organs, molecular structures, planets, … and have something physical to show or throw around during a science demo.
Just to name a few reasons why 3D printing is cool.
What is possible even cooler is the potential of printing tissues and organs. And now, for the first time according to a group of researchers in Tel Aviv, it has happened: a complete 3D heart was printed.
They started with some cells isolated from a sheet of fatty tissuefrom a human patient. These cells were reprogrammed to what’s called pluripotent stem cells. Pluripotent stem cells have the potential to give rise to many different cell types , depending on the biochemical cues they get – for example by changing the formulation of the culture media, which contains nutrients, hormones and other components to “feed” the cells.
In this case, the cells were driven towards being heart muscle cells and blood vessel cells. By mixing these cells with a personalized hydrogel, consisting of collagen (remember, from the reindeer eyes?) and glycoproteins (proteins have a sugar molecule connected to it), the researchers created a “bioink”, a material that could be used to print cardiac tissue in the same way a 3D printer prints 3D structures using a plastic “ink”.
While the 3D printed heart – currently around the size of a rabbit’s heart – cannot beat yet, the possibility to be able to print custom organs, starting from a patient’s own cells and therefore eliminating an immune response, is of major importance for medical applications. To enable heart function, the heart cells would have to be taught how to contract in an organized manner, and create a beating heart.
Beating has already been achieved in heart organoids. Organoids are little mini-organs grown in a petri dish, that mimic the organization and function of an organ in a living organism. The difference between 3D printed organs and organoids, is that organoids are allowed to form their own structure and cell types, driven by the media cocktail they are given, while 3D printing positions already differentiated cells in a 3D scaffold. Heart organoids, starting from one or a few reprogrammed cells, grow into structured groups of cells that spontaneously start beating.
These organoids, however, don’t really mimic the structure of the heart unless you “force” structure by growing these mini-hearts in a mold, basically geometrically confining the cells to form a predefined structure.
A model of a pumping heart was developed last year, creating an in vitro biomimetic system that could help with drug discovery and studying cardiac diseases. While it doesn’t look as much as a heart as the 3D printed one developed by the Israeli research group, it’s still pretty amazing to watch this little blob of tissue beating under electrical stimulation:
In any case, I hope to see a combined version of all of the above: a 3D printed, functional heart. Nevertheless, this first (though debatable if they actually were the first) 3D printed heart is pretty awesome and has a lot of potential applications in medicine and clinical research. Not to mention that it looks pretty cool:
Sources used:
Noor N., Shapira A., Edri R., Gal I., Wertheim L., Dvir T. 3D Printing of Personalized Thick and Perfusable Cardiac Patches and Hearts. Adv. Sci. (2019), 1900344. https://doi.org/10.1002/advs.201900344
Ma Z., Wang J., Loskill P., Heubsch N., Koo S., Svedlund F.L., Marks N.C., Hua E.W., Grigoropoulos C.P., Conklin B.R., Healy K.E. Self-organizing human cardiac microchambers mediated by geometric confinement. Nat. Comm. 6 (2015), 7413. https://doi.org/10.1038/ncomms8413
Li R.A., Keung A., Cashman T.J., Backeris P.C., Johnson B.V., Bardot E.S., Wong A.O.T., Chan P.K.W., Chan C.W.Y, Costa K.D. Bioengineering an electro-mechanically functional miniature ventricular heart chamber from human pluripotent stem cells.Biomaterials 163 (2018), 116-127. https://doi.org/10.1016/j.biomaterials.2018.02.024
*Sudden realization that most (if not all) of this blog is me saying “Hey, did you hear about this science thing, it’s really cool!!”
A few months ago I lost my mood ring. Which is very discerning; I haven’t been able to tell what my mood is since then!
I was reminded of my lack of mood-reading device in Vancouver last weekend. I was in one of those fantasy-merch shops that sells lots of dragon statues. I was admiring their collection of mood rings and wondering whether I should buy a new, when I suddenly realized I didn’t actually know how mood rings work.
To the google!
Thermochromic materials
Mood rings don’t actually tell what your mood is (sorry). They do give some indication of your skin temperature, which I guess is slightly related to your mood but probably more related to the weather and how cold you’re feeling. Created in 1975 by New Yorkers Josh Reynolds and Maris Ambats, mood rings were a fad in the 1970s, and probably again in the 1990s if I remember correctly. To be honest, they’ve never really left the mystic thingumabob shops, or souvenir shops (as you might be able to tell by the Celtic knot design in the picture above; I bought the rings for my friend and me in a Scottish souvenir shop).
The change-changing part of a mood ring is a thermochromic material, i.e. a material that changes color (chroma -χρῶμα) due to a change in temperature (thermos – θερμός).*
There are different examples of thermochromic materials and a number of different applications. Those t-shirts that change in color if you press your hand on them. Those cups that change color when containing a hot liquid. Those little thermometer rulers that change color if you hold them in your hand. And mood rings.
Liquid crystals
The type of material in a mood ring, that changes color according to changing temperature, is a liquid crystal.
If you had some intro to chemistry at some point, you might remember hearing that crystals have a very organized structure, with atoms (or molecules) forming a lattice. Perhaps you did an experiment where you made salt crystals by evaporating water from saltwater in a dish. But you probably remember that crystals were not liquid.
Then what are liquid crystals? Basically, it’s a state of matter which lies in between liquids and crystals. Usually, liquid crystal molecules are elongated, so depending on their packing they have more crystal-like properties (dense packing) or more liquid properties (looser packing). Depending on their “phase”, i.e. structural organization and packing, the optical properties of liquid crystals change.
The molecules in a liquid crystal can take up different degrees of order:
No order; basically the material is a liquid with properties of a fluid. (A in the very professional sketch below.)
Some order; the molecules sort of align in the same direction, but not along a plane (B).
More order; the molecules start organizing themselves along planes (C).
Full order; all molecules are neatly arranged in a regular lattice structure. Wait, this is a full crystal! (D)
As stated, with changing orientation and order, the optical properties change, similar to the collagen from a previous post. Depending on how organized the molecules are, different light wavelengths are reflected by the mood rind “gem”. In other words: the warmer the mood ring gem gets, the less organized the liquid crystal molecules are, and that causes a shift in color.
So if you’re feeling unsure about your mood, mood rings don’t actually help, but I’ve found that they are quite a conversation starter. But now, instead of handing your ring to whoever exclaims “Oh cool! A mood ring! Can I try it on?“, you can also explain exactly how it (doesn’t) work.
* Using any excuse to use the Greek alphabet for something other than fraternity names. I now walk to work through Fraternity Lane (not the actual name), so I’m constantly reminded of the letter φ.
** Bonus pic – origami flowers from those same pieces of paper:
A few weeks ago, I went to a public lecture – attractively named “Wine Down with Science” – organized by UW Medicine and I’ve been trying to tell people about it ever since.
The first problem is that the topic of the talk is one of those words that I’ll always just struggle to pronounce on the first go:
I went to the event not knowing what it was going to be about. I was already sold when I read it was a public lecture about some groundbreaking research; any excuse to listen to science in a more informal setting. Turned out, it was good of me to go, because it was sort of about biophysics and biophysics is sort of my jam.
So what is the *insert long word here again*?
Proprioception you mean? According to the event announcement, the lecture title was: Out of Your Mind: The Inner Workings of Your Mysterious Sixth Sense. So proprioception is about seeing dead people?
Nope. In reality, proprioception is our ability to be aware of the position and movement of our body and its parts. Not having proprioceptive abilities is one of the reasons that man-mimicking robots fail at a lot of seemingly basic tasks. They have no internal feedback system to tell them how their parts are positioned or moving with respect to each other, making benign tasks hard to do.
With proprioception, we know exactly how our body is positioned: whether our arms are bent, our feet are flexed, our eyelids are closed (okay, there are other ways to tell). And that without having to look at those body parts. There are some known cases of people losing their sense of proprioception and it causes paralysis (if you have 10 minutes to spare, you should really check out this video about a man who lost his sense of proprioception but taught himself to walk using visual cues instead).
How can we study this proprioception thing?
This is where it gets even cooler. The lecturer – John Tuthill – explained how in his lab, they use a clever combination of lasers, genetic tools, virtual reality, and fruit-fly-treadmills to understand how proprioception works.
By making a fruit fly run on a floating ball, and surrounding it with screens, they can trick the fly into thinking it’s strolling somewhere outside and track the neuron activity during movement. Using a laser, they can turn off the proprioceptive neurons very locally (using something called optogenetics, but that’s for some other time). For example, if by blocking proprioception in one of the fly’s legs, i.e. stopping communication between the leg and the central nervous system, they temporarily paralyze that leg. After turning the laser back off, the fly trods on as if nothing has happened.
First of all, part of science is just understanding how things work. Knowledge for knowledge’s sake. But there are also some useful applications of this knowledge, such as helping people with movement disorders. And helping robot-designers to not make robots that seemingly stupidly fall over.
This talk was by John Tuthill, PhD, Assistant Professor of Physiology and Biophysics. His work is really cool. Go check it out.
Occasionally, a colleague passes by my desk and says something along the lines of “Hey, did you know that *insert fun – usually science-related – fact here*?”
The other day, this exact thing happened:
“Hey, did you know that reindeer’s eyes turn blue in the winter?”
The question was prompted by the magnificent drawing of an octomoose (name pending) on the white board in our office. How the octomoose came about, is not that interesting a story, but I would want to share with you that we held a poll to determine the name of the 8-tentacled creature. My vote was for moctopus. I did not win (6 vs 3 votes).
So now that winter has come to an end, let’s talk about those weird reindeer eyes.
Discerningly, the first suggestions google search gave me when I typed in “reindeer eyes” was “reindeer eyes recipes”, which is just creepy; though actually clicking through reassured me that it was about chocolates and cookies (phew).
The struggle did not end there. The next page I found had a photo of a “summer reindeer eye” vs a “winter reindeer eye”:
Jackpot? Nope. The photo was photoshopped (quite obviously). Sigh. This is turning out to be a lesson in fact-checking.
However, I was not chasing a myth. It’s still true that reindeer’s eyes change color from gold in the summer to blue in the winter. Proof of this is in a scientific paper (hurray for backtracking to the source) which features some very creepy photos of reindeer eyeballs:
The explanation as to why this happens seems to lie in the reflective layer that sits behind the retina: the Tapetum lucidum. A lot of mammals have this layer; you might have noticed it when shining a light in your cat’s eyes (and survived to tell the tale). This extra layer helps animals see when it’s all twilight-y. It reflects light that passes through the retina, causing the light to pass through the retina twice, giving the light-detecting cells of the retina a second chance to detect any photos. When you see that yellow glow in your cat’s eyes, it’s the light reflecting right back at you off their Tapetum lucidum.
The next bit of eye knowledge you need to understand the changing reindeer eye color is the fact that pupils widen and shrink depending on how much light is available. Dilated pupils allow more light to enter the eye, and hence more photons can be detected by the light-sensing cells in the retina.
In the arctic winter – basically 3 months of darkness – the reindeer’s pupils are continuously dilated. The constant effort to keep the irises open constricts the small vessels that usually drain fluid out of the eyes. This, in turn, causes a pressure buildup within the eye, which compresses the Tapetum lucidum.
The Tapetum lucidum is mostly made up of a protein called collagen. This fibrous protein is a hydrogel, an ordered mesh of fibers that absorb and retain fluid. However, when this mesh is compressed, the fluid is squeezed out (like when you squeeze a sponge) and the orderly rows of collagen fibers become more tightly packed. The type of light that is reflected by the Tapetum depends on the spacing between these fibers. When they are “normally” spaced, like in the summer, longer wavelength light (yellow) is reflected, giving the Tapetum a golden color. When tighter packed, blue wavelengths (which are shorter) are reflected, giving the reindeer blue eyes.
In short, in the months of darkness, reindeer’s pupils are permanently dilated, leading to the swollen eye, leading to compression of the collagen fibers, changing the color that is reflected by the Tapetum.
Research is still ongoing because even though the mechanism behind eye-color-change has been explained, the effect on eye function is still unclear. Perhaps this change in eye color changes the sensitivity of the eyes. And why do other arctic animals, who also live through months of perpetual darkness, not have this cool change in eye color?
However, one thing is for sure, Rudolph’s red nose cannot be explained by science. Yet.
The original source: Stokkan, Folkow, Dukes, Nevue, Hogg, Siefken, Dakin & Jeffery. 2013. Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer. Proc Roy Soc B http://dx.doi.org/10.1098/rspb.2013.2451
A few months ago, my friend Vale asked me to collaborate with her on a project. I remember it going something along the lines of:*
Vale: “So, I’m working on this project and was wondering if you wanted to be part of it.”
Me: “Yeah, of course.”
Vale: …
Me: “Wait, what is the project?”
Say “yes” and ask questions later
Though probably not valid for every situation, I knew that in this case, I would be fine to say yes before knowing what I’d said yes to. If you’ve read any of my other stuff, you know that I’ve done various “scicomm”** projects like developing a “Build a LEGO-microscope” workshop and organizing a lecture series called “The Science of SciFi”. These were both in collaboration with Vale (and occasionally other people). She’s also the one who got me into Bright Club!
It seems that we work well together. And working together on a new project (without even knowing what it was), sounded like a lot of fun.
Art-meets-science
By now, I (obviously) know what the project is. It all started with #inktober, an art challenge that challenges illustrators to draw something using the medium of ink every day for a whole month (can you guess which?). Vale took up that challenge, and made it even more of a challenge by deciding to bundle her illustrations in a book.
Every drawing is based on a scientist*** that she considers a personal inspiration and is linked to a word from the prompt list. She’d post the result with a short explanation of why she chose that scientist for that prompt. Sometimes they were pretty obvious (at least to me, of course “stretch” is about D’Arcy Thompson!), some rather funny.
And then I come in.
Inspired by her drawing, I write a short text to go along with it. Sometimes it’s an anecdote. Sometimes it’s a quote. Sometimes it’s a short story about the scientist’s life. I try to make it as informative, engaging, unique and fun as I can.
It’s kind of awkward for me to sit here and write about a book I’m involved in, trying to get it made, aka trying to get the campaign funded. Like really, really awkward. So I’ll only do it once****:
Every little helps. Pledging helps, obviously, but spreading the word does too. If you like science, engineering, and math; and if you like amazing art; and if you like stories (and if maybe you also like us)… please share our project and help us make this book a reality!
Both Vale and I have found inspiration in these scientists, and we have found inspiration working on this book together. Hopefully, it will inspire you too.
*end of sappy book promo – I’ll be back next week with the usual science, nerdiness and hopefully some “Eureka!”s*
*Severely paraphrasing. This was months ago. I might have also dreamt it but on the other hand, this project is happening so I guess that means the conversation happened too.
** or “science communication”, which is the umbrella term I use for STEM-related outreach, workshops, talks, and other similar activities.
*** in the broad sense of the word. They could be mathematicians, or engineers, or inventors. Creative STEM-people if you will.
**** on this blog, to be clear. My other social media channels will be swamped! Like, I actually really care about this project and am super excited and want to see it happen!
All of the art work shown in this post is by Valentina, and within the #inkingscience project.
Here’s a riddle for you: what hangs in every chemistry class in middle and high school, leads to the creation of several nerdy t-shirts, and celebrated is 150th birthday yesterday?
Okay, it’s not a very funny riddle. Nor is it a very difficult one. The answer is: the periodic table of elements, first published on the 6th of March 1869 – exactly 150 years minus-one-day ago – by the Russian chemist Dmitri Mendeleev.
From Alchemy to Chemistry
In the olden days, we would have turned to alchemists to ask our questions about fundamental elements and what stuff makes up stuff. Even though alchemy was not really a “science” in the pure sense of the word – it relied heavily on spiritualism, philosophy and even magic – it set the stage for what would later become chemistry. And while alchemists were mostly trying to turn random metallic rocks into gold, or brew an elixir for eternal life, they were the first that attempted to identify and organize the different substances occurring in nature. The Elements.
The earliest basic elements were considered to be earth, water, air, and fire. The discovery of what we might call “chemical elements” really kicked off in 1669 in Germany, by a merchant by the name of Henning Brand. Like many chemists-avant-la-lettre (alchemists), he was trying to discover the Philosopher’s stone. However, like many muggles, he was not acquainted with Nicolas Flamel and did not succeed (Side note: Nicolas Flamel was actually based on a real person!). Instead, while distilling urine – as you would while trying to create eternal life – he discovered a glow-in-the-dark substance: phosphorous. And with that, the element finding had begun.
Chemistry can be considered to have originated in 1789, when Antoine-Laurent de Lavoiser wrote what is said to be the first modern chemistry textbook. In this book, he defined an element as a substance that can not be broken down into a simpler substance. A fundamental particle. This definition lasted until the discovery of subatomic particles (electrons, protons, and neutrons) in the 1930s. Lavoisier’s list of elements included things like oxygen, hydrogen, and mercury, but also light.
Let’s glaze over most of the 19th century, where multiple different scientists realized that the atomic weights of elements were multiples of that of hydrogen (William Prout) and how there was a certain periodicity in terms of physical and chemical properties when the elements were arranged according to their atomic weights (Alexandre-Emile Béguyer de Chancourtois). The early attempts to classify the elements were based on this periodicity, and eventually, our Mendeleev came along.
“Chemical Solitaire”
The Russian chemist Dmitri Mendeleev is the father of the modern periodic table. In fact, in Belgium, we call the periodic table of elements “Mendeleev’s table of elements”. After (allegedly) playing “chemical solitaire” on long train journeys – quite common in Russia, I’m sure – he came up with a classification method based on arranging the elements by atomic mass and classifying them according to their properties. Elements in one group (column) have the same number of valance electrons: the number of electrons in the outer shell of the atom and available to react with other elements. Elements in the same column therefore from bonds with other elements in the same way, and form similar types of materials.
Because there were some gaps in the table – some atomic weights missing – he predicted the existence of elements that were yet to be discovered, and what their chemical properties would be. And this is what made his classification method so ground-breaking.
And indeed, in 1885 germanium was discovered, with properties – as predicted – similar to silicon. Same for gallium in 1875 (similar properties as aluminum) and scandium in 1879 (similar properties as boron), filling up some gaps in his periodic table.
The gaps are filled
Since 1869, the gaps in the periodic table have been filled, and new elements are discovered or created every few years adding to the high end of the table. The last update to the periodic table was in 2016, when the elements nihonium (113), moscovium (115), tennessene (117) and oganesson (118) were added to the list.
So today – okay, yesterday – we celebrated 150 years of chemical element classification, the anniversary of the periodic table of elements, and the collective pain of decades of highschoolers memorizing atomic masses and the number of valance electrons.