Allotropes, graphene, Neanderthals, carbon
Chemistry of Yore and Now
Comments | Print friendly | Subscribe | Email Us
Chemistry of Yore and Now
For many the field of chemistry is a terra incognita, an unknown world. This is odd if one considers that humans are virtually chemistry factories, ingesting, processing and producing chemicals throughout our lives. We routinely use a wide variety of chemicals without ever thinking of them in those terms, from detergents to medications. Besides, with all kinds of wonderful electronic gadgets, who needs to know anything about chemistry or chemicals anyway? On top of that, we are constantly told that chemicals are dangerous to our health. Everything else, including meteorites are too.
You might not believe it, but the Neanderthals (80,000 years ago) and their later cousins, the Cro-Magnon people (30,000 years ago) had an inkling of chemistry. Their cave paintings in France and Spain survived for tens of thousands of years simply because they used extremely stable, mineral-based pigments including mercury, iron and manganese type minerals. For example, just look at any of the many pictographs from ancient caves around the Pyrenees (Fig. 1). They appear to be done yesterday, clear and crisp. The lesson is to use stable pigments for your art; some knowledge of chemistry helps for that.
The Mongol emperor Genghis Khan (1162-1227) and his cohorts also knew some chemistry. They had invented black powder (gunpowder), the stuff modern civil war enthusiasts use to fire in their re-incarnated flint-lock guns and cannons. At the time of Genghis (Fig. 2) black powder was used mostly for more illuminating purposes, i.e. fireworks. When Genghis’ marauding army moved west into the heart of Europe it was using bow and arrow as their weaponry. The barrel and bullet idea came later.
We still have fireworks, barrels, and bullets, and their chemistry is even more important today. The innovation-seeking company, Innocentive, Inc., recently announced it was seeking ideas for “novel highly energetic materials.” That’s a nice way of saying explosives with yet more punch or more powerful chemicals.
Modern chemistry has its roots in medieval times. Just as with many modern governments, most rulers then had a problem: money (then counted in gold and silver) was always in short supply. So, these rulers were happily investing in the “forward looking statements” of alchemists (Fig. 3) of the day, i.e. their promises to create gold and silver from low cost materials. They just needed some “start-up funds” for their undertakings.
None of the medieval alchemists ever succeeded in delivering the goods envisaged (Fig. 3). As we known now, their attempts were doomed to fail, but they tried and, along the way, gave rise to a whole new field of science: modern chemistry!
Since medieval times chemistry has changed a lot. From haphazard beginnings it has seen explosive growth in knowledge and understanding. There are now some 70 million distinct chemicals known to mankind, many of which have quite specific biological properties. One new compound has a rather simple structure (Fig. 4) but is said to be a candidate for drugs to fight several diseases including epilepsy and Parkinson’s disease. Additional new chemicals are currently being registered at a rate of approximately 7 million per year.
According to Wikipedia, carbon is the fourth most abundant chemical element in the universe by mass.
Carbon is much maligned these days. Even people in high places seem to think that this element (one of less than 100 naturally occurring ones) is evil but nothing could be further from the truth.
Carbon occurs in two principal forms, called allotropes. One is diamonds, the other one graphite. Both are important industrial materials, however with vastly different properties. Pure diamond is extremely hard and colorless.
In contrast, graphite is black and soft, but more important than diamond. In fact, graphite and its mono-molecular layer component, called graphene (Fig. 5) is currently the new “wonder” material with all kinds of potential applications and uses. The Nobel Prize in Physics for 2010 was awarded to its inventors Andre Geim and Konstatin Novoselov for for groundbreaking experiments regarding the two-dimensional material graphene. The rigid two-dimensional structure of graphene gives it unique electronic and mechanical properties within the plane.
Without carbon on planet Earth, there would be no life on it at all.
The many millions of chemical derivatives of carbon are part of our bodies, food, and medicinal compounds. Each life form on earth needs these carbon-based chemicals, from the lowest bacterial strain to the highest life forms.
Their chemistry makes the difference.