Sam Kean

Most stars just fuse hydrogen into helium, but larger stars can fuse helium into other elements. Still larger stars, in turn, fuse those elements into slightly bigger ones, and so on.

Everywhere in the universe, the periodic table has the same basic structure. Even if an alien civilization's table weren't plotted out in the castle-with-turrets shape we humans favor, their spiral or pyramidal or whatever-shaped periodic table would naturally pause after 118 elements.

If you had to sum up chemistry in one sentence, it might be this: Atoms need to have full shells of electrons to feel satisfied, and different elements steal, shed, or borrow different numbers of electrons to achieve a full shell.

Those of us raised in modern cities tend to notice horizontal and vertical lines more quickly than lines at other orientations. In contrast, people raised in nomadic tribes do a better job noticing lines skewed at intermediate angles, since Mother Nature tends to work with a wider array of lines than most architects.

If studying the periodic table taught me nothing else, it's that the credulity of human beings for periodic table panaceas is pretty much boundless.

In some sense, what you might have suspected from the first day of high-school chemistry is true: The periodic table is a colossal waste of time. Nine out of every 10 atoms in the universe are hydrogen, the first element and the major constituent of stars. The other 10 percent of all atoms are helium.

Polonium is, frankly, pretty useless, and no country in the world except Russia bothered to refine it by the late 2000s.

Brains, you see, vary a lot from person to person - they vary as much as faces do.

After about 1940, scientists generally stopped looking for elements in nature. Instead, they had to create them by smashing smaller atoms together.

Whereas recessive traits require two bad copies of a gene to become noticeable, a dominant trait expresses itself no matter what the other copy does. A benign example of dominance: If you inherit one gene for sticky wet earwax and one gene for dry earwax, the sticky earwax gene wins out every time.

When it comes to the periodic table, the United States really blew its chance to make a name for itself. If you look over a map of all the elements named for cities, states, countries, and continents, it's not surprising that European locales dominate the map.

When first presented with the jumble of the periodic table, I scanned for mercury and couldn't find it. It is there - between gold, which is also dense and soft, and thallium, which is also poisonous. But the symbol for mercury, Hg, consists of two letters that don't even appear in its name.

The price of diamonds can vary greatly depending on size, cut, color, and other factors, including whether they have a history. But because of the rarity of blue boron diamonds, they often fetch more money than gems of similar quality.

If stem cells divide equally, so both daughter cells look more or less the same, each one becomes another stem cell. If the split is unequal, neurons form prematurely.

The brain, which is plastic when young, must be exposed to certain sights early in life, or it will remain blind to those sights forever.

Brain surgery couldn't happen without the patient's own active voice to guide the work. The patient is part of the surgical team here, perhaps the most important part, and above all, that's what makes neurosurgery different.

The amygdala is indeed crucial for monitoring our environment and deciding what's worth getting worked up over. Once the amygdala determines this, however, it merely trips another circuit to actually produce the panic.

The idea of critical windows extends beyond just vision, of course: almost every system in the brain has a critical window when it needs to experience certain stimuli, or it won't get wired up properly. The most obvious example is language: if you don't learn a language early on, it's nigh impossible to become truly fluent.

America was probably Europe's equal scientifically by the end of World War I and certainly surpassed it after the chaos of World War II.

Guinea pigs are practically synonymous with experiments. Lab rats have become the workhorses of modern medicine. Genetics owes a huge debt to the humble fruit fly. There's almost no branch of the life sciences, in fact, that hasn't leaned heavily on one animal or another.