Rowena Rae - Chemical World: Science in Our Daily Lives

The periodic table of elements. The elements were first placed in this arrangement in the 1870s

ITS ELEMENTAL: Of the 118 elements on the periodic table, 92 are found in nature. The rest are made by humans.

Imagine a family of cave dwellers huddled in their cave, eating raw meat. They are made of chemicals and so is everything around themthe cave walls, the meat, the bed of dried grass. Suddenly a spark blows into the cave from a nearby wildfire and whoosh! The grass catches on fire.

Why are we talking about fire? Fire is an example of a chemical reaction. In a chemical reaction, one or more chemicals transform, or change, into one or more different chemicals.In fires case, a fuel (such as grass) plus oxygen in the air get kick-started by a spark and transform into carbon dioxide plus water. As this transformation happens, heat and particles (smoke and soot, for example) are released.

Early humans would have known about fire from wildfires and volcanoes before they knew how to make or control fire themselves. Archaeologistsscientists who study human historyhave found old fire pits, ashes and other evidence showing that people started making fires deliberately at least 700,000 years ago. As well as warmth and cooked food, fire gave people a place to gather and socialize. Knowing how to light a fire was an important step in human evolution. Fires were also one of the earliest types of pollution.

These ax heads found in present-day Hungary date to the years 2000600 BCE, which are within the time frame of the Bronze Age. bridgemanimages.com

Early humans used stones and bones as tools. Then they started working metals like copper and tinalso basic elementsinto spear tips, knives and bowls. Later humans found a way to mix copper and tin to make a new, strong metal called bronze. Bronze is an alloy, meaning that basic elements have been melted together in a physical reaction, not a chemical one. The basic elements are still there but in a new arrangement.

Heres a way to remember the difference. In a physical reaction, you can get the original ingredients back as individual things. For example, when you spread jam on bread, the jam is still jam and the bread is still bread. In a chemical reaction, the original ingredients change into something new and you cannot get them back. For example, when you cook an egg, the gloppy white and runny yolk become firm. You cant get the original white and yolk back. Seems like magic, but its chemistry.

The Alchemists Mystical Lair

An Iranian painting of alchemists from 1893. bridgemanimages.com

Have you read the first Harry Potter book? If so, youll remember the philosophers stone (or sorcerers stone, depending on where you live). This stone turned metal into gold and produced a liquid giving immortality (eternal life) to the person who drank it. Author J.K. Rowling created a fantasy world, but did you know that the idea of the philosophers stone is true? In Rowlings novel, an alchemist named Nicolas Flamel created the stone. In real life, alchemy was an early form of chemistry. There was a real Nicolas Flamel too. He lived in France in the 1300s and 1400s. Centuries after his death he became known as an alchemist, but there is no evidence that he really was one.

Real-life alchemists tried to transform metals into gold, discover a medicine to heal all ills and create an elixir of life to give humans immortality. Alchemists didnt achieve any of these goals, but they still made discoveries. They found elements like phosphorus and zinc, and they created mixtures like gunpowder (the first explosive).