State two pieces of evidence for believing that matter is made up of molecules.?

Question

It's an A-Level Physics tutorial class question.

Answer 1

(1) Substances like water (a liquid) can be split up into 2 separate elements of oxygen and hydrogen (gases).

(2) When weighing gases like oxygen, it's found that the weight is always twice of what's expected. This is due to the fact that oxygen atoms combine to form O2 molecules. Oxygen is never found in isolation in nature.

Answer 2

All matter is made up of particles called atoms and molecules (as opposed to being continuous or just including particles).
Although matter has been studied for millennia, it is only in the last two centuries that we have developed a good understanding of what it is. Early Greek philosophers theorized that matter could be broken down into smaller and smaller pieces, until it reached some "most small" piece, which they called an atom. This philosophical idea was later contested by Aristotle and his followers, who thought that matter was made up of four fundamental elements: earth, air, water, and fire. (A fifth element, quintessence, was believed to make up the sun and stars). Aristotle's philosophy dominated Western science for centuries, so a satisfying model of matter took a long time to develop.

The first steps towards understanding matter came from chemistry. European chemists performed experiments on various substances, watching how one substance combined with another: what new substances the two substances could be combined to produce, and how much of the new substance there would be. Out of these experiments arose the idea that substances were composed of individual particles, which the scientists called "atoms", based on the ancient Greek (and now you see the main benefit of a classical education: modern physicists, who are generally not classically educated, give physical quantities dorky names like "top quark" or "strange quark" rather than the far more elegant "proton" and "electron").

So the first evidence that matter was composed of atoms was produced by scientists in the late 18th century. Among them was John Dalton, an English schoolteacher whose studies of the atmosphere led him to create an early "periodic table".

Answer 3

The fact that you're alive would be one. Breathing, eating and drinking would be colossal wastes of time if yer body weren't breaking the intake down into usable chunks (molecules). If apples were just a solid chunk of homogenous material it would simply pass through you. Another one would be that water has entirely different properties than either oxygen or hydrogen and therefore then something is happening when they get together. And since they can only get together in certain ways (there is, as far as I know, no H6O7 or H11O9) then we can surmise that the result of combining hydrogen and oxygen (aside from blowing the place up) is the water molecule.

Answer 4

1) Atomic Structure
2) Molecular Structure