A chemical element, often just referred to as an element, is a type of atom that has the same number of protons

in its nuclei as all the other elements of that sort, of that particular substance. So all

atoms with one proton are hydrogen, atoms with 24 protons are chromium, and so forth. That is already a dramatic oversimplification of what's going on here, but the important thing to know,

for the purposes of this conversation, is that all matter in the universe, all substance that

takes up space in the universe, and anything that is not the theorized dark matter that we are still

speculating about as we explore the wider universe, all matter is made up of elements. So all the

stuff that is stuff that we consider matter rather than theoretical dark matter, it is all

elements of different kinds. Elements are primarily categorized

based on their atomic number, which is equivalent to the aforementioned number of protons

that they have in their nucleus. So helium has an atomic number of two. Lithium has an atomic number

of three. Xenon has an atomic number of 54, and germanium has an atomic number of 3, xenon has an atomic number of 54, and germanium has an

atomic number of 32, and all of those numbers are equivalent to the number of protons that they have

in their nucleus. As far back as the 18th century, we already knew of some relatively easy to

research elements like platinum, tin, mercury, and zinc,

as these elements can be seen with the naked eye. They can be mined with simple tools.

And as a consequence, we have, in some cases, been working with them since the days of ancient Greece.

Some Greek philosophers of the era, including Aristotle, actually came up with rudimentary

conceptions of how these building blocks fit together to make up everything, at the time,

assuming that earth, water, fire, and air could be mixed together in countless different ways

to give us things like wood, soil, stone, and so on. Now, this did not turn out to be true,

of course, but it was closer to the truth than we could have known at the time, and so on. Now, this did not turn out to be true, of course, but it was closer to the

truth than we could have known at the time. And although there were a lot of interesting experiments

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