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In the same way that biology has the fundamental idea that all organisms want to reproduce and pass on their genetic information, and that evolution accounts for the diversity of life, what are some of the ideas that tie chemistry together? Apart from all the specifics, what is chemistry really about at its heart?

Apologies if this sounds like a really strange question.

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    $\begingroup$ There are atoms. They bind to each other... and that's pretty much this for general stuff. If you have a feeling you need to apologise while writing a question, then consulting it in chat before asking may be a good idea. $\endgroup$ – Mithoron Mar 27 at 20:54
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    $\begingroup$ Atomism - All (regular) matter is made of atoms. $\endgroup$ – Nicolau Saker Neto Mar 28 at 3:40
  • $\begingroup$ Chemistry has so many fields, and the question could have so many answers. I would say organization: no chemistry, no organized matter in the universe, no life, no minerals, no drugs, no polymers, no quantum mechanics... $\endgroup$ – The_Vinz Mar 28 at 4:51
  • $\begingroup$ Your idea about biology is not quite right. Species survive if they generate offspring. Which is a bit too trivial to count as a fundamental principle. $\endgroup$ – Karl Mar 28 at 7:35
  • $\begingroup$ I meant in the sense that species do need to pass on genetic information otherwise they will die out, regardless I think it gets the point across. I was thinking about this for a bit and came to the conclusion that the fundamental idea that ties chemistry together is that electrons and atoms want to lower their energies. This is why they form bonds so that they are more stable. Idk I do feel like I'm missing something massive I just can't figure out what $\endgroup$ – MirzaTheCutiePie Mar 28 at 8:22
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The fundamental principle of chemistry is probably the conservation laws : energy and matter. Maybe also the universal attraction between positive and negative charges and the repulsion between similar charges. These laws have no exceptions, as far as I know.

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    $\begingroup$ One might argue that those are in fact the fundamental principles of physics. $\endgroup$ – Ivan Neretin Mar 27 at 20:29
  • $\begingroup$ @Ivan. Of course. The fundamental principles are the same in physics and chemistry. $\endgroup$ – Maurice Mar 27 at 20:37
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    $\begingroup$ One might ask what is the reason for the very existence of chemistry as a science, then. $\endgroup$ – Ivan Neretin Mar 27 at 21:18
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    $\begingroup$ @Ivan. That is a good question. In France, chemistry is a chapter of physics, at school, like optics or electricity. $\endgroup$ – Maurice Mar 27 at 21:30
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    $\begingroup$ @IvanNeretin Mandatory xkcd. $\endgroup$ – Blackhole Mar 28 at 12:18
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This is an inherently subjective question. It's very difficult to come up with an answer that isn't just a fundamental principle of physics. My personal opinion is the following:

Chemistry is the study of interacting electrons.

Now, obviously the electrons are only near enough to interact because the positive charges of nuclei don't let the electrons fly away. Fundamentally, however, all of chemistry can be described in terms of electron densities, which is the basis of density functional theory.

This is not just a theoretical construct either. In every field, people are talking about different types of bonds and different electronegativities. If you think about organic chemistry, reaction mechanisms are described in terms of electron-pushing, which is some highly abstract way of talking about the dynamics one might find if you could solve the time-dependent Schrodinger equation for arbitrary lengths of time.

Even things that seem to have nothing to do with electrons, such as nuclear magnetic resonance, are often useful because they key in information about the where electrons are localized via chemical shifts.

Also, this definition manages to distinguish chemists from physicists because very often physicists don't care about solving for the energy of something to the sixth decimal place. Whereas, as a computational chemist, I sometimes worry that I might actually need to get that electronic energy out to the ninth decimal place...

So, my opinion is that chemistry is the study of interacting electrons, and chemists care very deeply about the details of those interactions.

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  • $\begingroup$ It is perfectly right. But is it really an answer to the question ? $\endgroup$ – Maurice Mar 27 at 22:09
  • $\begingroup$ I think so. I'm just saying there's really one fundamental principle. There are definitely lots of other ideas and quantities which show up repeatedly, but their relevance to chemistry is in some way connected to the interactions of electrons. $\endgroup$ – jheindel Mar 27 at 22:43
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    $\begingroup$ You seem to have a strong bias against nuclei. I would say the electrons play the game but the nuclei create the field. $\endgroup$ – Buck Thorn Mar 28 at 12:47
  • $\begingroup$ @Buck Thorn Haha fair enough. I've got nothing against nuclei. The chemistry wouldn't happen without them. It's just that much of the variety in chemistry seems to come from how the electronic structure of a material responds to it's environment. This response is due to a change in the electrons. Obviously they are changing from some base configuration which was only adopted because the nuclei were there in the first place. Your point is well taken though. $\endgroup$ – jheindel Mar 28 at 16:13
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    $\begingroup$ I only answered the question because I had actually thought about this before and view electrons as being the prime object in chemistry. I'm not saying nothing else matters. Only that very often, the electrons are the most important part of the problem. On the other hand, vibrational spectroscopists tend to think about the nuclei in the field of the electrons, so I'm sure many vibrational spectroscopists would disagree with this view. Ultimately, whether you look at nuclei or electrons are two sides of the same coin, as the BO approximation tells us. $\endgroup$ – jheindel Mar 28 at 20:56
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Chemistry is different from physics in that its focus has historically been on understanding what gives rise to the variation of matter, rather than asking "what is matter", which is one of the more profound questions physics asks. By extension chemistry also concerns itself with how matter can be transformed within this manifold of possible forms.

Chemistry is an extremely broad field that encompasses just about anything you can think of, as reflected in the great variety of subfields with hyphenated or compound names: geochemistry, astrochemistry, biochemistry, physical chemistry (not to be confused with chemical physics), nuclear chemistry, analytical chemistry, inorganic chemistry, organometallic chemistry, organic chemistry, chemical engineering, petrochemistry, agrochemistry, food chemistry, quantum chemistry, electrochemistry, among many others and including only those that include "chemistry" in their name (unlike say molecular biology, protein science, materials science and many other fields which are arguably also chemical sciences, or contain a strong chemical component).

This is why chemists proudly state that chemistry is the central science.

For more information on the great scope of chemistry you may want to check what branches exist within a professional society such as the ACS (American Chemical Society).

Addendum: Given the question "what are the central principles found throughout chemistry", emphasizing the role of the electrons makes sense, since describing their behavior is a key concern for understanding the structure and reactivity of compounds. But I'd say the fundamental principles are "quantum mechanics" and the "principle of charge" (the latter given as an answer elsewhere) and not restrict myself to the electron.

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  • $\begingroup$ I did not include computational chemistry in the list because it is not about the chemistry of computers, it is theoretical. $\endgroup$ – Buck Thorn Mar 28 at 3:43
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Chemistry seeks to describe, among other things, chemical changes in the world. All spontaneous changes obey a law, and that is that they increase the entropy of the universe. Hence, a fundamental principle of chemistry could arguably be:

dS > 0

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  • $\begingroup$ As for the conservation laws, the increase of entropy is not specific to chemistry. It is also valid for physics. $\endgroup$ – Maurice Mar 27 at 22:15
  • $\begingroup$ @Maurice Of course, but as you said, the fundamental principles are the same in physics and chemistry. $\endgroup$ – arevmelikyan Mar 27 at 22:21

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