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We owe our terms atom and element to early ancient Greek philosophers such as Democritus and Empedocles, but science owes something more fundamental to these philosophers who wrote about phusis $\phi \upsilon \sigma \iota \varsigma$ from whence we get the term physics. “Phusis” is usually translated as nature, although its meaning more nuanced than that.
The nature of something is the way it happens to be, or the way it “is”, often with the understanding that the only thing that “is” constant, is change. Empedocles’ four elements; air, earth, fire and water and, the two forces, love and strife (attraction and repulsion) is a way to explain the nature of things, as is Democritus’ atoms in motion.
As systems of scientific explanation, these are more basic than our modern periodic table and atomic models. Nor are they the result of empirical observation, but rather they are the result of a kind of reasoning about existence and things. In order to understand these systems, we should appreciate where they came from, rather than criticize them for not doing modern science.
Before philosophy began, things were defined by tradition and custom. A thing was defined first by being familiar and second, by the tradition that had been handed down about it. The older the tradition, the more authoritative it was. It had survived the test of time. People also were defined in their culture by tradition in much the same way. They were members of, and had loyalty to, a family clan. The taint of murder and other crimes shamed the family and transferred from generation to generation. Occupations were hereditary. In other words, if it was good enough for your father and for his father, it was good for you.
Tradition and custom were the way of the world for thousands of years. Ancient Greece was the first to get out of this pattern. How was it that Greece began to get out of the Dictates of Tradition as the sole guide for what everything is and how it is?
The Greeks, unlike more mature cultures such as Egypt and Babylon, consisted of hundreds of modest little communities, each with their own laws, their own customs, and their own traditions. Going from one community to another, a traveler could lose his awe of his own native traditions and come to wonder which of the hundreds of different sets of traditions were the best. Finally, he realizes that while several communities had aged traditions that withstood the test of time, no community had the best beliefs about all things, the world and people.
The search for the best traditions, laws and customs leads to the search of nature. Much of this search originally was a search into what we would call the physical nature of things, and only later beginning with Socrates, would become a search for human nature, including into the political nature of man. Nature is something older than tradition, even if “it” does not actually exist, but is only a potentiality. For example, it is part of the nature of water that it freezes at $0^{\circ}C$. One can live in the tropics and never have seen water freeze, but it still would be part of the nature of water that it freezes at $0^{\circ}C$.
Tradition emphasizes stability, continuity. Nature, on the other hand, tends be about how and why things change. Now, with the experimental method, Science has us creating changes in a thing and observing with the use of mathematics and advanced instrumentation what happens in response to those changes. However, all this started with the ancient Greeks going beyond tradition and looking at phusis, exploring the nature of what is best. Whether we have found the best or whether we are even still in sight of that path, is a question for another time, which for now, I will leave it up to the reader to judge.