2012 CHRISTMAS LECTURES®: The Modern Alchemist
When medieval alchemists staged spectacular stunts in front of royalty they never revealed the secrets of their mystical potions and fire-breathing creations. Today's chemists can perform equally impressive feats, but they do so to explain and explore the extreme frontiers of our material world. Dr Peter Wothers is the Modern Alchemist. In this year's CHRISTMAS LECTURES®he will unpick the chemistry of the world around us - looking at Air, Water and Earth - three of the original ancient Greek ‘elements' that tantalised alchemists for centuries.
Lecture 1: Air: The Elixir of Life
Filming date: Tuesday 11 December, 6.00pm
Take a deep breath. Inside your lungs is a mixture of highly reactive and incredibly stable gases. Oxygen is the most reactive constituent. When we eat it's these O2 molecules that seize electrons from our food to give our bodies the energy to live. Add a third oxygen atom and we make ozone, a gas so reactive that it's toxic if we breathe it in, but high up in the stratosphere this gas protects us from the sun's radiation. Add a carbon atom and we produce carbon dioxide, a greenhouse gas responsible for warming the planet. We will unravel the puzzle of how and why these compounds of oxygen hold the key to the viability of life on the planet.
Nitrogen, the most common element in air, is an unreactive gas, but a key atom in every cell in every living thing on Earth. How can we imitate nature to bring this suffocating gas alive? Even less reactive are the Noble or inert gases. They're so stable they are the only elements that exist naturally as individual atoms - but what is it about them that make them so inert? And how can we excite these gases enough to join the chemical party? We've come a long way from the days when alchemists thought air was a single element.
Lecture 2: Water: The Fountain of Youth
Filming date: Thursday 13 December 2012
Water is essential to life since every reaction in our bodies takes place in it. But what makes this fluid so special? What happens when you add a lighted splint to a mixture of hydrogen and oxygen? Kaboom! But why? What makes this particular rearrangement of atoms to form water so explosive? Can we tap this energy release to provide environmentally friendly solution to our energy problems? Plants have the ability to reverse this reaction by using the energy from sunlight to release oxygen from water. We are starting to learn how to do the same. In this lecture we unpack how energy lies at the heart of chemistry.
We'll also look at the salts contained in water. Once again we will see the startling difference between a compound and its constituent elements. Take sodium chloride - aka table salt. Sodium is a soft silvery metal that explodes with water; chlorine a deadly poisonous, choking green gas. Both elements are lethal to us, but after they have met, a dramatic change takes place. The sodium and chloride ions that form are essential components in our bodies. They help generate the electrical impulses that make our brains and nerves work. We begin to see how chemistry plays a vital role in our lives.
Lecture 3: Earth: The Philosopher's Stone
Filming date: Saturday 15 December 2012
The rocks that form planet Earth have always fascinated alchemists. Deep in the bowels of the Earth they thought the metals literally grew in the rocks and that one metal over time matured into another. They dreamed of replicating these natural processes turning ‘base metals' into gold. Today the extraction of minerals and metals from rocks has made fortunes, but not quite in the way the alchemists imagined. We now know many rocks are the result of oxygen combining with different elements - each with individual properties. Breaking the strong bonds between oxygen and these elements has always been a challenge. Humankind learned how to release copper in the Bronze Age, and iron in the Iron Age, through smelting. Now we can extract even more exotic materials.
By understanding the properties of materials, such as the silicon present in computers, or the rare earth magnets generating our electricity in wind turbines, we are entering a new era of chemistry in which we can engineer electrons in new configurations for future technologies. We can now put together the unique cluster of protons, neutrons and electrons that form each of the 80 elements in exciting new ways. If the ancient alchemists were alive today they'd be dazzled by the wonders created by the Modern Alchemist.