17 molecules that changed the world

All molecules are not created equal. Some have saved billions of lives, wreaked environmental havoc or made the world a more colourful place. Here’s a selection of molecules that have changed the course of human history.

When British microbiologist Alexander Fleming stumbled upon penicillin in 1928, he couldn’t have imagined the impact it would have on modern medicine. Fleming noticed that Petri dishes with mould on them grew no bacteria, and in doing so discovered the first antibiotic. Before penicillin came into widespread use in the 1940s, wounds and diseases such as syphilis were killers; antibiotics have since saved an estimated 200 million lives.

Salt paved the way for modern civilisation; it was used to preserve vegetables and meat as long as 4,000 years ago. This gave our ancestors the freedom to store food for hard times, travel long distances and live in harsh climates. Salt is also an important ingredient in the production of chemicals, soap and paper. Sodium chloride is in such high demand that in 2006 alone, 240 million tonnes were produced.

As the key ingredient in gunpowder, potassium nitrate allowed humans to propel bullets from guns and, in doing so, changed the face of warfare. Today, there are more than 500 million handguns in circulation, causing at least 1,000 deaths every day. The formula for gunpowder was likely discovered in the 8th century, although it wasn’t until the 13th century that it was first used in canons.

Aspirin is the most widely used drug in the world, with more than 100 billion tablets consumed annually. The active component, salicylic acid, originally from willow bark, was used as a folk remedy as long ago as the 5th century BC. But it wasn’t until 1897 that German chemist Felix Hoffman managed to synthesise aspirin in a pure and stable form, making it one of the earliest synthetic drugs. Aspirin is now taken for a huge variety of afflictions, from fever and arthritis to the prevention of heart attacks, stroke and dementia.

It’s hard to imagine how life might have smelled for the human race before the invention of soap. More fastidious hygiene has also been important for stemming the spread of disease. Sodium stearate, the active ingredient in soap, works its magic by helping oil to dissolve in water. According to the United Nations Children’s Fund, hand washing with soap prevents up to 1.4 million deaths per year through acute respiratory infections.

In 1954 the first silicon transistor initiated what has become a A$160 billion global market in semiconductors. Silicon is a key component of computer chips and circuits and it’s estimated that there are currently more than one billion computers in use worldwide. Silicon is also used in solar cells, waterproofing treatments and seals, explosives and breast implants.

Natural rubber has been gathered from the sap of plants for centuries. But rubber only began to be used widely after 1839, when Charles Goodyear found a way to make it strong, durable and elastic. In 1931 U.S. chemist Elmer Bolton developed a synthetic version, and in 2005 we produced 21 million tonnes, with tyres and tubes accounting for 56% of consumption. Other applications include gloves, rubber bands and balloons. Even some rockets and missiles are powered by synthetic, rubber-based fuels.

As the principal component in glass, silicon dioxide was used as early as 5000 BC. All the panes of glass in the world today cover about four billion square metres. Glass has also been essential for test tubes, telescopes, microscopes, mirrors and camera lenses.

By far the most popular plastic, polyethylene is used in grocery bags, artificial joints and plastic bottles. It’s even found in chewing gum. In fact, polyethylene is so ubiquitous that it’s hard to imagine life without it. But in 1933 when English chemists Eric Fawcett and Reginald Gibson discovered it, they thought of it as nothing more than a waste product. Over 70 years later, more than 60 million tonnes of polyethylene are made each year; but there is a downside, as much of it ends up in landfill where it takes hundreds of years to degrade.

DDT — C14H9Cl5
In the 1950s and 1960s, DDT was used to eliminate malaria from Europe and North America in a program that, according to the World Health Organisation, saved an estimated 25 million lives. However, as early as the 1940s scientists had begun expressing concern over hazards associated with the use of DDT, and extensive research has since implicated the organochlorine insecticide in the poisoning of humans, animals and the environment. As a result, its use has been banned or restricted in many countries.

A potent painkiller, morphine was first isolated by German pharmacist Friedrich Sertürner in 1804. To this day, it remains the most important drug used to minimise suffering in terminally ill patients, particularly cancer sufferers. No other drug is as long-lasting and effective at managing severe pain. Despite this, 80% of the world’s population has access to just 6% of the world’s supply. Morphine is more widely distributed in the form of the illicit drug heroin, with an industry estimated at nearly A$100 billion annually.

In the early 20th century, the world’s growing population couldn’t find enough ammonia to fertilise all its crops. Due to the discovery of a technique to mass-produce ammonia, called the Haber process, an estimated two billion people are not starving today. We produce 100 million tonnes of ammonia for fertiliser each year, but it is also an important ingredient in explosives.

Iron accounts for at least 90 per cent of metal production. Without it we wouldn’t have powerlines or oil refineries. Iron is a key component of cars, trains, planes, ships, fridges, dishwashers and computers. As a chemical it’s also used in insecticides, water purification, sewage treatment and the production of ammonia. Iron was first smelted 3,500 years ago, but it wasn’t until English engineer Henry Bessemer’s invention in 1856 of an inexpensive way to mass-produce steel from iron that its use skyrocketed. In 2007 alone, 1,900 million tonnes of iron ore were produced, with 98 per cent of that used to make steel.

If your head is swimming, you’re seeing double and suddenly finding everyone attractive, chances are that ethanol is to blame. Worldwide, about two billion people enjoy ethanol, the intoxicant in alcohol. The average Australian, for example, drinks about 10 litres of pure alcohol each year. Historians suspect that it was accidentally discovered when our ancestors’ grain stores were drenched with rain and fermented by the Sun. The liquor reduces inhibitions, alters moods, impairs judgement and boosts sexual desire. Alcohol consumption is the third largest risk factor for disease in developed countries.

A country’s production of sulfuric acid is a good indication of its industrial might, because at some stage nearly every manufactured good comes into contact with this highly corrosive stuff. It’s used in mining, steel production, oil refining and chemical synthesis, and in the manufacture of fertilisers, detergents and plastics. No wonder it’s nicknamed “the king of chemicals”. Sulfuric acid was discovered in the 8th century, but it only became economically viable in 1746, when English chemist John Roebuck developed a way to produce it in bulk. In 2005 world production of sulfuric acid was estimated at 193 million tonnes.

As the principal component of the pill, progestin allowed women to separate sex from procreation, giving them unprecedented freedom and control over their lives. First synthesised in 1951 by Austrian Carl Djerassi, progestin stops ovulation by imitating the hormone progesterone. Between 1965 and 1995 global fertility rates fell from 4.9 to 2.8 children per woman, largely due to the pill. Today, more than 70 million women around the world use this oral contraceptive.

Scottish chemist Joseph Black discovered and isolated this potent greenhouse gas in the 1750s. At that time, man-made CO2 emissions were about three million tonnes per year. But by 2005, emissions from fossil fuels alone were 7.9 billion tonnes, with another 1.5 billion tonnes caused by forest clearing. Carbon dioxide is the second most important greenhouse gas (after water vapour), trapping heat in our atmosphere and increasing global temperatures via the greenhouse effect. Emissions continue to climb, so unless there’s a drastic turnaround, expect the sea level rises, extreme weather events and mass extinctions associated with a rapidly warming globe.

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