Why chemistry is so difficult ?

[Jon Richfield]

lol same, i hate biology and chemistry, you learn everything by heart, which is stupid, they don't show proofs and theories at school, so are geo and history.

You have no idea how saddening this is. I don't know what to do about it, but if you can escape the poison in the syllabus, and learn things with comprehension and make a point about seeing how they hang together, you can make sense out of geography, biology, geology, astronomy, and even in some cases and in some senses, even history and propaganda. It basically becomes a matter of alert observation and making connections without forcing connections.

Sometimes the process is subtle.

Try this one for an example. I was being dragged around a golf course in Western Australia. Oz is a fascinating continent but half totally alien to me and half misleadingly similar to my home ground. And a tree some 50m away from the fairway suddenly seemed to have the wrong texture in a particular tuft of foliage. I became intrigued, wandered off, and when I was just a metre or so from the branch, I realized that the foliage was sheltering a pair of tawny frogmouths. They were not part of the growing scheme of the tree, you see? You might say there was a logical discontinuity, right? I still don't know the species of Banksia, but my eye could tell that there was an inhomogeneity. Am I getting through?

I could not have done that before I had developed field experience that told me that there was more to a tree than brown trunk and green leaves.

But the birds were so well camouflaged that our photos failed. In real life we could see that the frogmouths were adapted to look like broken branches and in this respect their logic was so precise that of the hundreds of golfers that passed them daily, hardly one in a hundred ever spotted them, and then by accident.

Every non-trivial subject has its own logic. Not everyone has the aptitude to see it. But a bit of good hard work at the start might make the rest of the course a breeze, an enjoyable breeze, and enrich your world tremendously.

Trust one who has tried a few of the fields

Jon

 

[johncena]

I am having the same problem with matrices and determinants...it is really fun doing problems ,but i wan't to know where did this rules come from (rules for matrix operations & determinants)

 

[sponsoredwalk]

I am having the same problem with matrices and determinants...it is really fun doing problems ,but i wan't to know where did this rules come from (rules for matrix operations & determinants)

Have you ever heard of Linear Algebra?

If you're only learning about this stuff in high school then It doesn't surprise me that it's confusing you, it'll all make sense once you take linear algebra.

http://ocw.mit.edu/OcwWeb/Mathematics/18-06Spring-2005/VideoLectures/index.htm

http://tutorial.math.lamar.edu/Classes/LinAlg/LinAlg.aspx


Anyway, back to Chemistry, I got Linus Pauling's book the other day and have started it, it seems pretty good so far!

 

[walkerr]

Chemistry is about half way between Physics and Biology. In Physics, students learn to derive and utilize formulas. In Biology, there are no formulas, only memorization of facts. In chemistry, there are many "tools" which must be memorized before one can solve problems in chemistry. These include electron configurations, ionic charges, electronegativity values, nomenclature rules, element symbols, certain formulas, such as the ideal gas law, and many others.

The fact that these "tools" are presented without derivation in the General Chemistry course may present a stumblingblock to math and physics majors, who are not used to taking things on "faith". However, all of these concepts are rigorously proven in the Physical Chemistry course.

 

[chill_factor]

Things are not proven in lower division chemistry because new students are simply not good enough at math and physics to handle the proofs which are seriously hard to prove. Even something as "simple" as chemical bonding in H2+ (the simplest "molecule" possible, with just 2 protons and 1 electron) requires at the minimum a strong understanding of quantum mechanics, at least wave mechanics, with all the corresponding math. Multielectron atoms also cannot be derived with anything less than full on quantum mechanics.

If you tossed Ira Levine's "Quantum Chemistry" at a first year they're going to give up and major in psychology or business instead. Why do you think 1st year physics classes aren't going over conformal mapping to calculate capacitance of non-concentric wires and the like?

The reason the derivations are saved for 3rd year physical chemistry and 4th year quantum/computational chemistry (elective) is because they're simply too hard without already taking Calculus 1-3, Linear Algebra and ODEs.

Want rigorous derivation? You think you can handle it? "Molecular Quantum Mechanics" by Atkins and Ira Levine's "Quantum Chemistry" are good places to get started.

 

[JohnRC]

One of the reasons that chemistry is so difficult for almost everyone is that it involves so many very different conceptualization schemes. I note, for example, that the OP said that s/he has no difficulty with the formulas and with phys chem generally. All of us educators are used to students of chemistry having difficulty with the mathematical side, and I think that most of the replies have missed this particular point in the original post and proceeded to discuss the reasons why students have difficulty with the mathematical side of chemistry.

There are equally difficult problems in learning the inorganic/organic sides of chemistry as well -- more difficult for some, and not so often recognised by others.

(1) Generalizations and systems: The biggest difficulty that students have with the descriptive side of chemistry is recognizing the appropriate generalizations. They treat chemical properties as a number of individual facts to be memorised and regurgitated at examination time. After a while the sheer volume of facts becomes unmanageable. It is vital that a student make the breakthrough to recognise the patterns that properties follow, and to recognise the subtle variations that go with changing the structure. How properties of inorganic materials differ if you substitute an atom with another from the same periodic table group, for example, or how the behaviour of a particular organic functional group will change in a compound if you attach it to a heavier framework, or a sterically crowding framework, or an electron withdrawing framework.

The other side of this is that textbooks and teachers tend to over-emphasize similarities by "force-fitting" borderline cases, so that the real compounds that students actually meet in the lab do not quite match the expectations when a "rule of thumb" is interpreted as a strict law of nature.

(2) Symbolic representations: In most other branches of science, artificial representations are far less central than they are in chemistry. The bonding calculus pervades everything: single bonds, double bonds, polar bonds, ionic bonds, co-ordinate bonds. Students get terribly confused, and textbooks can get terribly dogmatic. The second chemical formula that most students learn to use is sulfuric acid: H2SO4. But there are three quite different ways of writing a structural formula for sulfuric acid, each of them valid in some ways, and problematic in others. It does not help when a particular textbook suggests that one of them is right and others are wrong. But it also can lead to confusion of you try to introduce students to the reality of the situation: nature does not know about formal charges or double bonds or co-ordinate bonds -- they are accounting devices introduced by chemists to approximately represent the situation. And there is the fact that the four oxygen atoms in sulfate ion are exactly equivalent does not fit with any structural representation until and unless we introduce the concept of six equivalent resonance structures, no less!

(3) While we are on the example of sulfuric acid, it is important to point out a third area where students of chemistry have difficulty -- understanding three-dimensional objects. The whole of the education system focuses on two dimensional media -- books, projector screens, computer screens. It is important to obtain a thorough understanding of 3-dimensional objects by actually handling them, not just visualizing them. Many of my students could not deeply understand why there were not cis- and trans-versions of the sulfuric acid molecule -- they just had to take it on trust! Nearly all students have difficulty understanding chirality, and even more difficulty in working with it in structures with more than one chiral centre. Or even recognizing when it would arise. (Most, for example, fail to recognize that 2-butanol is chiral unless it is pointed out to them.

A lot of the ways that chemists have to think are completely different to those employed in other areas of science, or indeed in non-science subjects either. It is small wonder that chemistry is found to be difficult.

 

[member 392791]

I've found the lab component of chemistry to be significantly harder than physics, while the physics theory is more difficult to understand. However I'm only comparing lower division chemistry and physics and extrapolating it to the entire field, I could certainly be wrong but most of my chemistry professors seem to be math-incompetent relative to the physicists.

 

[JohnRC]

I've found the lab component of chemistry to be significantly harder than physics, while the physics theory is more difficult to understand. However I'm only comparing lower division chemistry and physics and extrapolating it to the entire field, I could certainly be wrong but most of my chemistry professors seem to be math-incompetent relative to the physicists.

Only in Physical Chemistry is any sophisticated maths used as such. Analytical chemistry involves a lot of arithmetic, but sophisticated maths comes in only at the research level with differential calculus and statistics.

Many organic and inorganic chemists hardly need to use maths at all, and yet the sorts of manipulations they use to work out structural possibilities, reaction mechanisms, routes for synthesis really involve quite sophisticated informal mathematics in manipulations of bonds, formal electron transfers for reaction pathways ("curly arrows"), rough considerations of polarization effects, and the like.

They are deeply involved with manipulations of formal symbols that they use to represent substances, and with translations of these symbols at two levels :
• "accounting electrons" to "actual electrons", and
• "actual molecular scale machinations" to bulk material behaviour.

These fundamental parts of the modern chemical body of understanding are quite "mathematical" in their character, and yet are seldom if ever dealt with in the way that formal mathematics would approach them, and never incorporated into a formal mathematics syllabus.

 

[member 392791]

Right now I'm taking organic chemistry and it is by no means trivial..in fact I'm doing the worst in that class between linear algebra/diff equation and physics. I could be a more systematic thinker, but o-chem has something special about it that is making it very frustrating for me. The concepts don't seem that deep, but perhaps the way the questions are proposed is harder for me personally.

I mean there's no way isomerism is more complicated than vector spaces, but if you ask me to draw all isomers of C8H18 on the exam..I might not be able to do it.

 

[JohnRC]

Right now I'm taking organic chemistry and it is by no means trivial..in fact I'm doing the worst in that class between linear algebra/diff equation and physics. I could be a more systematic thinker, but o-chem has something special about it that is making it very frustrating for me. The concepts don't seem that deep, but perhaps the way the questions are proposed is harder for me personally.

I mean there's no way isomerism is more complicated than vector spaces, but if you ask me to draw all isomers of C8H18 on the exam..I might not be able to do it.

You are quite right, and this is exactly what I am talking about. A problem like this is not beyond the scope of a formal mathematical representation. But setting one up and getting it right is not a practical way to go about it in a test situation.

Chemists tend to approach this type of problem in a more instinctive, rule-of-thumb sort of way that would be frowned on by most mathematicians. And they do not always get the right answer.

For this particular problem a chemist would probably develop an algorithm that would be an attempt to make a systematic direct count --

----- chemist type algorithm ----
first there is octane.
Now what about heptanes -- how many different places can you put a methyl substituent? Three -- the 2, 3, & 4 positions. (A really clever chemist would here recognize that 3-methylheptane is chiral, giving rise to two different isomers. Most would not)
Next try hexanes. They can be either dimethylhexanes or ethylhexanes. How many of each? (and which of them, if any, are chiral?)
Then we can consider pentanes, which must be either trimethyl or ethylmethyl.
And that leaves a single tetramethylbutane, the only possibility, because any substituent longer than a methyl on a butane would make a pentane.
------

I venture to suggest that that is the way that most chemists would go about this problem, and that it is quite different to the approach that a mathematician or a physicist would use.

 

[DrDu]

At least in Germany, I see a serious problem with the formation of high-school teachers. They are trained to teach not only one subject, but two. However, these combinations can not be chosen freely. Most chemistry teachers have the combination chemistry/biology and most physics teachers physics/mathematics. So while the physics curriculum takes into account the mathematical background available at any given level, chemistry curriculum avoids mathematical arguments where possible.

 

[JohnRC]

At least in Germany, I see a serious problem with the formation of high-school teachers. They are trained to teach not only one subject, but two. However, these combinations can not be chosen freely. Most chemistry teachers have the combination chemistry/biology and most physics teachers physics/mathematics. So while the physics curriculum takes into account the mathematical background available at any given level, chemistry curriculum avoids mathematical arguments where possible.

That is also the case here in Australia DrDu. We also require high school teachers to be 2-subject trained, and we have a far less rigid structure than Germany. But most of our senior chemistry teachers are essentially biologists, because biology courses are a lot more popular than chemistry courses at university level, and biology graduates are a lot less employable.

In my particular state this is exacerbated by the general rule that a teacher cannot take a class at the top high school level in a subject unless they have at least a second year university level pass in that subject. But in the case of chemistry, biochem 2 is recognised as fulfilling that condition; it does not have to be chemistry 2.

So chemistry tends to be taught at high school level as a purely descriptive subject, centred on memorizing a lot of facts, and the systematic infrastructure and modes of thinking that are distinctive parts of chemistry are not understood nor expected by students. And that difficulty stands quite separate from a generally lower level of engagement with higher maths on the part of both teachers and students of chemistry.

When students hit university level chemistry, they still expect it to be a fully descriptive subject, and often they are quite resistant to developing a conceptual framework, so that they get overwhelmed by a huge number of facts that they cannot relate to one another. They have genuine difficulties with the whole of chemistry, not just the small part that might relate to an inadequate maths background.

 

[Borek]

This thinking - that chemistry is mostly descriptive - is popular throughout the world, not limited to Germany and Australia. Plenty of students are surprised that they need to use simple algebra to solve the chemistry problems ("what do you mean two equations with two unknowns, this is chemistry"). I have seen it personally in Poland, but judging from the forums it happens everywhere.

 

[DrDu]

Exactly, I remember that we spent a considerable time (at least one term) in high school on how to balance equations, using some vodoo formalism and then another term learning how to balance redox equations using this obscure oxidation number formalism.
It came as a revelation when I found out that both reduce to simple problems of linear algebra from the equations of conservation of atom numbers and charge.
Another term wasted on learning thousand special cases on how to calculate pH along a titration curve. Again instead of starting from the complete set of equations and then introducing approximations, only thousands of special cases were treated without showing first the general picture.

 

[Borek]

Another term wasted on learning thousand special cases on how to calculate pH along a titration curve. Again instead of starting from the complete set of equations and then introducing approximations, only thousands of special cases were treated without showing first the general picture.

You may like top-down approach presented here then: http://www.chembuddy.com/?left=pH-calculation&right=toc

 

[DrDu]

Yes Borek, your page is outstandingly pedagogical in this respect!
The only thing I mind is that there is no linux version of your calculators :-)

 

[chill_factor]

Also I have an issue with chemistry electives in college. Why do I get the feeling 90% of the electives are bio related? Do we really need "Biochemistry", "Advanced Biochemistry", "Chemical Biology", "Physical Biochemistry" "Computational Biology"... all as chemistry electives, while there's 0-1 classes on traditional chemistry things like electrochemistry or polymers? Or newer but not explicitly bio related topics in chemistry like surface science, nanofabrication and colloids?

I mean, you learn things deeply in research, not classes, of course, but what about those who just want to take a class in something and not necessarily do research in it? How do you even do research without first taking a class in something and making an informed decision that its interesting and deserving of research?

Shouldn't the school actually teach what industry is using? Or at least what they expect students to know to do well in their own graduate programs in physical chemistry? I mean, I look at the curriculum for some physical chemistry departments, and think, how many chemistry students have the background to do it? How many could make an informed decision that "hey that research on nanotech was pretty cool" when most would never even see the "big picture" of what the current status of the field was and only would instead know the 10000000 interpretations of biology? Shouldn't the school at least teach a class on things that a sizable chunk of the faculty are doing?

I went to a big state university with a well known physical chemistry program and 100 majors graduating a year. If its like that here, then what's it like elsewhere?

 

[aroc91]

Also I have an issue with chemistry electives in college. Why do I get the feeling 90% of the electives are bio related? Do we really need "Biochemistry", "Advanced Biochemistry", "Chemical Biology", "Physical Biochemistry" "Computational Biology"... all as chemistry electives, while there's 0-1 classes on traditional chemistry things like electrochemistry or polymers? Or newer but not explicitly bio related topics in chemistry like surface science, nanofabrication and colloids?

I mean, you learn things deeply in research, not classes, of course, but what about those who just want to take a class in something and not necessarily do research in it? How do you even do research without first taking a class in something and making an informed decision that its interesting and deserving of research?

Shouldn't the school actually teach what industry is using? Or at least what they expect students to know to do well in their own graduate programs in physical chemistry? I mean, I look at the curriculum for some physical chemistry departments, and think, how many chemistry students have the background to do it? How many could make an informed decision that "hey that research on nanotech was pretty cool" when most would never even see the "big picture" of what the current status of the field was and only would instead know the 10000000 interpretations of biology? Shouldn't the school at least teach a class on things that a sizable chunk of the faculty are doing?

I went to a big state university with a well known physical chemistry program and 100 majors graduating a year. If its like that here, then what's it like elsewhere?

Definitely not. The chem electives at my school include organic, advanced organic, biochem, analytical, instrumental, inorganic, advanced inorganic, and physical.

 

[chill_factor]

Definitely not. The chem electives at my school include organic, advanced organic, biochem, analytical, instrumental, inorganic, advanced inorganic, and physical.

physical is not an elective here... you have to take a year and that's all there is to it. same for inorganic, its required. organic is lower divsion here, analytical is lower division here too.

advanced organic is so close to bio, to me anyhow, that it might as well be part of bio. organic doesn't use math or physics and its applied mostly in the pharmaceutical industry just like bio is, so to me its the same stuff.

i guess what i was looking for was an "applied physical chemistry" class about things that is actually used in industry. let's say physical chemistry of colloids. There's like 5 faculty in my alma mater that do colloids. There's not a single class on colloids. How do we know that colloids is interesting and want to do research in it? what if we're interested but don't want to commit?

Sure you might say "read yourself" but then why can't bio guys "read themselves"?

i'm in physics now so i have no stake in this, but my concern is for how students are not employable because they're not learning what industry does except instrumental analysis which is just 1 class. colloids are used all the time in industry; why are they not sponsoring classes in colloidal thermodynamics? surface characterization is a huge part of analytical chemistry, yet we spend all the time on small molecule stuff, and there's no "theory" class for surface science, just a materials lab. same with nanofabrication; that's an important part of applied physical chemistry yet where's the classes in it? Look, professors in colloids are teaching stuff like "chemistry of cooking", ok, so its not like they don't have the resources.

why does it have to be pharmaceuticals or bust?