John Browne - Seven Elements That Have Changed the World: Iron, Carbon, Gold, Silver, Uranium, Titanium, Silicon

WHY SEVEN?

T he number seven has always held a central place in myth, music and literature. The world was created in seven days; there are seven notes in the diatonic scale; and, according to Shakespeare, there are seven ages of man. In conceiving this book, I was also drawn to the number seven and so I asked myself: which of the seven chemical elements help us best to understand our world and how it came to be? I also thought about which have had the greatest influence on my life and which I have experienced most directly.

Carbon, which in combination with hydrogen forms the bulk of crude oil, was obvious. So too was iron, the backbone of all industry since the eighteenth-century Industrial Revolution (and without which no oil could be extracted). Silver came next to my mind as the element that made possible photography, one of my lifelong passions. Looking for further inspiration, I found in my library my school copy of the periodic table, which organises the elements according to their chemical properties. As I scanned the chequerboard, from left to right, I passed along the elements, each containing one more proton in its nucleus than the last.

First is hydrogen, vitally important in combination with so many other elements to form the structures of life and, as a result, fossil fuels. made silicon another obvious choice for inclusion.

Appearing in its world-changing form at the same time as silicon in the 1940s was titanium, the next element I stopped at. Once it was going to be the miracle element, a dream that did not quite work out. But what most drew me to it was its little-known use as a whitening agent in almost everything that is white. I learnt of this through business with Quebec Iron and Titanium in Canada. It surprised me then, and continues to astound me now.

Traversing the remainder of this line, I passed a number of familiar metals: iron, cobalt, nickel, copper, zinc. All of them are so important but, I wondered, which one actually changed the world. I stuck with my choice of iron and left copper behind; electrical engineering will have its fair share with silicon.

I passed silver, the element of photography, and then in the line below reached gold. Its universal allure led to its use in coins, the basis of currencies for centuries and the foundation of international trade. Gold became a great motivator for global expansion and imperial ambition. But the same attraction has led many to commits acts of immense cruelty. It continues to captivate us today.

Finally, I reached the bottom of the periodic table, six elements in tow. Here I came to uranium, whose nucleus, having accumulated so many protons and neutrons on the journey down the periodic table, is very unstable. That characteristic defined the post-war era on a day in 1945 in a city in Japan, and for that reason it is the seventh element.

Time and again, while writing this book, I have revisited the periodic table, questioning this choice of seven elements and questioning the choice of the number seven. Iron, carbon, gold, silver, uranium, titanium, silicon; each time,