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How much Chemistry in Physics

  1. Oct 7, 2012 #1
    Im taking a 2nd year Chemistry class at my university and i'm struggling.
    I'm very good a math and physics. How much knowledge of chemistry will you need in physics or a major in physics? I see a lot of sub atomic physics and particles and quantum physics etc.. Will I need to master chemistry?
  2. jcsd
  3. Oct 7, 2012 #2
    depends on what you do.

    In particle and plasma physics chemistry is totally useless.
  4. Oct 8, 2012 #3


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    On the other hand experimental physicists tend to work with the most nasty chemicals even chemists don't like to experiment with. I am thinking of etching silicon surfaces with hydrogen fluoride, to give an example.
  5. Oct 8, 2012 #4
    Well isn't Chemistry and particles directly related?
  6. Oct 8, 2012 #5


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    You may be mistaking particles for molecules.
  7. Oct 8, 2012 #6


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    Particle physics is the physics of subatomic particles - hadrons and their components (quarks and gluons), W, Z, and Higgs bosons, photons, leptons and neutrinos. And maybe other particles, if they exist.

    Nuclear physics builds atomic nuclei, based on those hadrons (here: protons+neutrons).
    Atomic physics builds atoms, based on those nuclei and electrons.
    Chemistry builds molecules, based on those atoms.

    You need some physics for chemistry, but no chemistry for particle physics (unless it is required to build a detector, for example).
  8. Oct 8, 2012 #7
    So if i'm understanding right Chemistry is more compounds. Particle physics deals more with just electrons, protons etc..
    Electrons and protons are also used in chemistry as well though, I just cant seem to draw the line between them, i'm sure physicists know a lot about chemistry.
  9. Oct 8, 2012 #8


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    It is mostly a matter of energy involved. Energies in particle physics are either much higher or much lower than energies in chemistry, so you usually deal with completely different phenomena.
  10. Oct 8, 2012 #9
    Well I've never met a physicist that could make a good brew.

  11. Oct 8, 2012 #10
    Well if you are dealing with protons than you are dealing with elements, therefor you are dealing with chemistry.. Where is my thinking flawed.?
  12. Oct 9, 2012 #11


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    You are ignoring the energies involved. Proton with energy high enough will not react as a chemical entity.

    Perhaps you can think about it this way - high energies mean high temperatures, in high temperatures most elements are highly ionized - and they don't behave the same way they behave in the test tube. This is no longer situation that chemists are trained to deal with.

    On the other hand, at very low energies we are dealing with substances that are very cold. That means they don't have enough energy to overcome typical activation barriers - so they don't react (chemically) with each other.
  13. Oct 9, 2012 #12
    Let's put it this way: You can think of Chemistry as a subset of Physics--APPLIED physics, if you will. Physics is required to build the laws of chemistry because physics is just a more general science than chemistry. This doesn't work in reverse: You don't need to know anything about chemistry to understand all the laws of physics and how to solve physics problems. I've found that a basic background in chemistry helps a bit here and there, but it really isn't necessary.

    Knowledge of protons and electrons on a basic level does not constitute Chemistry. Chemistry is the study of how bound proton-electron systems (atoms) interact with other atoms to form molecules and how those molecules join together to form chemical compounds. You can do all of the difficult quantum mechanics to study this subject and never have to take a pure "chemistry" course in your life. Chemistry offers a better, easier way of thinking of these processes though. Knowledge of chemistry offers very little insight into the fundamental nature of the electrons and protons and other particles; field theory, wavefunctions, particle decay, all that good stuff--THAT'S particle physics. And so particle physics and chemistry are NOT one and the same, or similar at all, though there is a LITTLE bit of overlap. The branch of physics that most closely connects with chem is atomic physics, probably.
  14. Oct 9, 2012 #13
    Some do but I cosider that view condescending at least.

    What technique, uniqe to Physics, would you employ to demonstrate that there is no such substance as 'vis vitalis'?

    (This was one of the great breakthroughs due entirely to Chemistry)
  15. Oct 9, 2012 #14
    And Physics made many a breakthrough independent of mathematics and even rewrote the book on a few things regarding math, but that doesn't mean I wouldn't consider it to be applied math, in a most basic form. Not trying to be condescending, and it's not that I don't consider chemistry to be a science in its own right, but if there is no physical basis to your chemistry, what is there?
  16. Oct 9, 2012 #15
    So what's the answer to my question?

    I can use formulae supplied by applied maths to calculate stresses in the members of a particular structure, but the ability to arrange members and their sizes, materials etc is the subject of another discipline.

    Similarly I can use physical methods to perfom chemical analyses, but the ability to choose and operate methods is the province of Chemistry.

    I think the OP recognised and made a distinction.

    By implication ther are other disciplines than Physics, even you have recognised this by quoting applied maths.
    Do you believe the only two disciplines are Maths and Physics?
    Last edited: Oct 9, 2012
  17. Oct 9, 2012 #16
    Well, that would depend on what the heck "vis vitalis" is...

    EDIT: Oh, do you mean as in the theory of Vitalism?
    Last edited: Oct 9, 2012
  18. Oct 9, 2012 #17
    When did I say this? I don't understand why you are antagonizing me on this topic. I only meant to simplify the difference between chemistry and physics in order to help the OP understand. I apologize if it seemed like I was dismissing chemistry.
  19. Oct 9, 2012 #18
    Applied math is not physics in my opinion. Applied math is, say, proving the existence and uniqueness of the Navier Stokes equations. You don't prove existence, uniqueness, singlevaluedness, etc. in physics. It is taken for granted.

    The easiest way to distinguish applied math and physics is that applied math has mathematical proofs, physics has experimental verification, and mathematicians don't give a * about units or constants.

    There's more stuff in chemistry like transport phenomena and chemical kinetics that's simply not taught in a physics curriculum and that's just physical chemistry which is close to physics. Physical chemistry isn't just quantum and stat mech. Even within stat mech there's more practical stuff taught in chemistry classes like molecular mechanics and hands on practice with Monte Carlo that's not covered in physics classes in favor of more formalism. There's also the whole problem of organic chemistry and biochemistry... you get what I'm saying here?

    been there done that =) etched glass with HF and measured mechanical properties. turns out that etched glass is far stronger than non-etched glass.
  20. Oct 9, 2012 #19
    Nope. Protons are almost never used in chemistry. You write H+ but there's no free proton, its H3O+. In fact a central approximation of chemistry is the Born Oppenheimer Approximation - nuclei do not move on chemically relevant (electron dynamics) timescales.

    Chemistry deals with the dynamics of atoms, molecules, solids, their interaction with electromagnetic radiation and the creation of useful products and services created from manipulating atoms, molecules, solids and electromagnetic radiation. That implies that things like the fact that the proton interacts through the strong force, that anti-matter exists, that the electron can interact through the weak force, mass-energy equivalence, etc. are irrelevant.

    You don't need to know too much about electrons or protons to do chemistry. Indeed, many theories are semi-classical instead of quantum because dealing with the wavefunction of say, a solid, is simply impossible. You don't need that sort of resolution. So we approximate it as balls with springs. Turns out it captures many essential features of solids, such as the existence of phonons and properties such as the energy gap between optical and acoustic phonons.
  21. Oct 9, 2012 #20
    I agree and would add that a knowledge of physics is more use to a chemistry than a knowledge of chemistry is to physics.

    For instance chemists need to know the difference between protons and electrons (physics) but I doubt many physicists need to know the difference between an elctrophilic reaction and a nucleophilic one (chemistry).

    Which brings me to the idea that much of chemistry is about reactions, rather than just molecules themselves.

    Finally I would observe that a knowlege of structural chemistry is of use to those studying crystal physics. Structural chemistry about about the spatial disposition of the atoms in individual molecules and molecular combinations such as solids.

    go well in your physics career.
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