Throughout history, people have believed some crazy things.
In the Christian Middle Ages, alchemists believed that man’s soul was divided in two after the fall of Adam and that if only it could be purified, then man would be reunited with God.
They believed if they could uncover the secret of ‘purifying’ everyday materials into gold, then they would also discover the secret of purifying the soul.
Needless to say that it didn’t work out.
At the time, they believed that everything in the universe was made up of four ‘elements’. Earth, water, air, and fire. This idea came from Aristotle, and it was accepted for thousands of years. It took until 1789 for a French chemist called Antoine Lavoisier to publish a treatise on thirty-three elements, which included oxygen, hydrogen, iron, and gold, and it formed the basis of modern chemistry.
Something I was delighted to find out is that modern science has actually discovered the ancient secret of turning other metals into gold. You can read about it here, but you blast mercury with radiation so that it becomes unstable, and a small portion of it will decay into gold. The only catch is that the process costs way more than the gold’s worth, and that irradiating your soul won’t purify it, it’ll just give you cancer.
So far we’ve discovered one hundred and eighteen elements, which are also known as different types of atoms. The best way to categorise them is by the number of protons the atom has in its nucleus, which we call the ‘atomic number’, and we organise them with a weird grid called the periodic table.
The periodic table is usually thought of as a pretty boring thing. It conjures up high school exams and rote learning (at least it did for me) but it’s really one of the most powerful ideas that humanity has ever thought of.
It’s quite literally the framework of modern chemistry and materials science.
It was invented by a Russian teacher called Dmitri Mendeleev as he was preparing a textbook for his class. He fell asleep and envisioned the complete arrangement of the elements in a dream.
I saw in a dream a table where all elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper, only in one place did a correction later seem necessary.
His genius was in recognising that properties of certain elements (like mass, freezing and boiling points, whether it’s hard or soft, or conducts electricity) repeated ‘periodically’ when you organised them by atomic number.
As soon as he wrote down his table (this was in 1869) he realised there were multiple elements yet to be discovered, and using his table he accurately predicted their properties.
Ever since, the periodic table has helped us plan the creation of new molecules and materials by telling us about the basic ‘building blocks’ involved. Volumes, properties, and reactivities are all clear at a glance.
We now know that all atoms are made up of the same components (protons, neutrons, and electrons), just different quantities of them. The quantities completely determine an atoms behaviour, from the volatile fluorine to the inactive neon.
Atoms like fluorine or caesium, which just have to gain or lose one atom respectively, are super reactive. They’ll tear electrons of other atoms to get what they want.
When you combine the two together, you get some otherworldly chemistry.
Atoms that have a complete outer shell, like neon, have no desire to donate or share any electrons. This keeps their charge neutral, so they rarely react with any other atoms at all.
While every atom occupies a unique place in the periodic table, as we move across it, patterns in behaviour emerge.
Chlorine is directly below fluorine, meaning it also has to gain just one electron. It is also reactive and dangerous but it’s heavier too, giving it behaviours that aren’t a copy of fluorine’s, but they are similar.
When atoms bond together to form molecules, their unique attributes create a huge array of molecules with their own properties. These properties of atoms and molecules are responsible for much of the complexity of our world.
But, something that the periodic table does not really show is that while each element has a fixed number of protons, the number of neutrons it has can also vary.
These variants are called isotopes and they are fundamental in understanding elements, particularly man-made ones.
There tends to be a stable ratio of protons to neutrons, and if the ratio falls too far on either side, the atom will decay by emitting protons and neutrons as radiation until it becomes stable.
This is how we can create gold out of mercury – by bombarding it with so many neutrons that the ratio becomes unstable, and the mercury decays into gold.
To understand isotopes we need a different graph: one that shows not just every type of element, but every type of atom that is possible.
The best one I’ve seen is the one below. The vertical axis is the number of protons (i.e. each row is a different element. Hydrogen is the first row, gold is number seventy-nine etc.), and the horizontal axis is the number of neutrons.
The bluer it is, the more unstable the atom is.
When we split an atom in two in a nuclear explosion, it releases a ton of energy and tends to form atoms that don’t have a stable ratio.
These unstable atoms are called nuclear waste, and they can emit radiation for tens of thousands of years or longer. Because of its longevity, nuclear waste is almost certainly going to be one of the lasting artefacts of human civilisation.