Noob question on Chemistry Basics

[Veylon]

I've suddenly have a burning interest in understanding how chemistry works at the lowest possible level. Now, from what I understand, chemistry works based on how many protons/electrons atoms have vs. how many fit in the shell which determines how they connect to each. Theoretically speaking, if you know that, you know everything there is to know about how that atom works at a chemical level. Going from there, it should be possible to determine what will happen if you put a bunch of chemical X and chemical Y together just with pencil and paper or with a simulation. Now, I know there's temperature and stirring (giving the chemicals a greater surface area with one another) that have an impact, but it seems like it ought to be a simple thing to predict what will happen.

I've visited a few Chemistry websites, but they seem to fragment this questions into a whole array of different types of reactions. Oxidizations, Acids and Bases, Organic Chemistry, etc. It seems like there should to be a few general rules that underpin all this stuff. I get that combining H2 and O2 adds up to water, but I don't understand, from an electron basis, why the bonds holding those two chemicals together normally break to allow it when they are in each other's presence.

So what is it that I'm not getting here?

 

[Calibanbutcher]

A few things apparently:
If you want to understand why the bonds break/don't break under any given circumstance, you need physics. And lots of it, preferably.

Also, chemistry really isn't that simple. If you want to get a grasp on things, why don't you try something along the lines of the "horrible science" or "XYZ for dummies". They usually provide a broad overview whilst not being too boring and afterwards, if you are interested in reading more, you could go for the "real" books on any given subject encompassed within the label "chemistry".

 

[WoW Killer]

I get that combining H2 and O2 adds up to water, but I don't understand, from an electron basis, why the bonds holding those two chemicals together normally break to allow it when they are in each other's presence.

I haven't done any chemistry since A-levels, but here's my understanding. They don't. You need to add heat to break those bonds. Without heat, H2 and O2 will happily exist side by side, because they already have complete shells. Now if you had lone hydrogen and oxygen atoms together, they'd combine to create water. A typical reaction starts first by breaking down compounds into individual atoms through adding heat, and then they recombine into new compounds (which releases heat).

 

[Albino Boo]

Ok you are on the right track with electrons. Electrons orbit the nucleus of the atom, these orbits are grouped together according to shape and know as shells. The most stable form is when the outermost shell is full. So in the case of hydrogen it only has 1 electron but its outermost shell, the S shell, is full at 2. However, just in the case of hydrogen, its more stable to to empty the s shell. Oxygen's outermost shell, the p shell, is full at 6. Oxygen has 8 electrons and is arranged 1s 2 2s2 2p4, in other words the 1st s shell has 2 electrons the 2nd s shell has 2 electrons and the p shell has 4 electrons. The atom will be more stable with 6 electrons in the outer shell so its 2 short. H20 comes about because hydrogen is more stable with no electrons and oxygen is more stable with those 2 added electrons.

Its gets more complicated when you are dealing with the F shell because the electrons there are fairly lose and 1/2 half filled shells comes into play, but that's the basic reason why. Atoms are trying to get into the most stable state of having their outermost electron shell full.

 

[Darken12]

Going from there, it should be possible to determine what will happen if you put a bunch of chemical X and chemical Y together just with pencil and paper or with a simulation. Now, I know there's temperature and stirring (giving the chemicals a greater surface area with one another) that have an impact, but it seems like it ought to be a simple thing to predict what will happen.

AHAHAHAHA oh goodness I am so sorry, I don't mean to be insulting at all, but that just makes me laugh out loud. If only my job was that simple! Sadly no, that's your baseline assertion and that's where it goes wrong.

You can't predict how a chemical will behave simply going on how many protons or electrons it has. There are many forces of attraction and repulsion at work, and those have a much greater effect on chemical behaviour than the composition of the chemicals themselves. You have polar attraction, non-polar attraction, semi-polar attraction, polar repulsion, semi-polar repulsion, Van der Waals forces, hydrogen bonds and many, many more. Each chemical is unique and each of its interactions with another chemical is also unique, and changing the conditions in the system (temperature, pH, energy, motion, electrostatic forces, other chemicals, pressure and so on) changes the results dramatically.

I've visited a few Chemistry websites, but they seem to fragment this questions into a whole array of different types of reactions. Oxidizations, Acids and Bases, Organic Chemistry, etc. It seems like there should to be a few general rules that underpin all this stuff. I get that combining H2 and O2 adds up to water, but I don't understand, from an electron basis, why the bonds holding those two chemicals together normally break to allow it when they are in each other's presence.

So what is it that I'm not getting here?

That goes on based on your previous assumption, that Chemistry is just a set of rules that allow us to easily predict results. Oh, dear. If only.

Chemistry isn't Physics. It's based on Physics, sure, but Chemistry has its own rules and outcomes that we are still trying to elucidate.

In the case of O2 and H2, it's actually extremely hard to get the electrons to separate from the bonds they have already formed. You need to saturate a container with both gases, in the right proportions (or else you might end up with H2O2 or some other oxygenated compound), and you need to provide both gases with sufficient energy for the electrons to break their bonds. If you're lucky, you will have multiple ruptures in both elements and instead of reforming with themselves, they will reform with each other, and you'll get water vapour.

 

[SckizoBoy]

I've visited a few Chemistry websites, but they seem to fragment this questions into a whole array of different types of reactions. Oxidizations, Acids and Bases, Organic Chemistry, etc. It seems like there should to be a few general rules that underpin all this stuff. I get that combining H2 and O2 adds up to water, but I don't understand, from an electron basis, why the bonds holding those two chemicals together normally break to allow it when they are in each other's presence.

So what is it that I'm not getting here?

To answer that particular question... and I'll build on this:

I haven't done any chemistry since A-levels, but here's my understanding. They don't. You need to add heat to break those bonds. Without heat, H2 and O2 will happily exist side by side, because they already have complete shells. Now if you had lone hydrogen and oxygen atoms together, they'd combine to create water. A typical reaction starts first by breaking down compounds into individual atoms through adding heat, and then they recombine into new compounds (which releases heat).

Heat is not necessary. It's the easiest way of doing it, but not the only way. All you need is some sort of energy input. Also, a correction to the above, molecular hydrogen and molecular oxygen don't have the best of relationships, even at RTP, because of the lower entropy of water over its elemental components in molecular form, so the reaction will still take place, just slowly. Pressure will force it ahead as well.

The H[sub]2[/sub] covalent bond is naturally quite weak, so it takes very little to break it up (creating a stable dipole in molecular hydrogen without breaking the bond is actually quite difficult). Once molecular hydrogen breaks up, irrespective of how the bond is broken, the lone pairs from oxygen will swarm all over it and trigger the breakdown of its double bond, mainly because the combined enthalpies of the four bonds (in molecular H x 2 & O[sub]2[/sub]) is greater, by quite a bit, than the four bonds in 2 x water, such is the stability of O-H, whether in water, the hydroxonium ion, or the hydroxide ion.

Now, with electron counts, it's all well and good knowing what's what in terms of configurations (I won't bother regurgitating what [user]albino boo[/user]'s said), but knowing the enthalpies of the bonds as well as relative stabilities of particular electrons is key to knowing reactivities and the 'intuitiveness' of certain reactions. That way, you know which (& why) salts are insoluble. *shrug*

 

[Smertnik]

You're probably better off just getting a book on basic chemistry if you're that interested in the subject. It'd provide you with way more information than anyone here would care to write down.

 

[bojackx]

H20 comes about because hydrogen is more stable with no electrons and oxygen is more stable with those 2 added electrons.

You mean each hydrogen atom is more stable with 2 electrons than 1? The electrons from the hydrogen aren't given to the oxygen, they are shared with it. Oxygen is happy with a full 6 electrons in its p-orbital, and hydrogen is happy with a full 2 electrons in its s-orbital, so by sharing the electrons it means that both atoms are happy. Sure, the hydrogens become slightly-positive as its electrons are pulled toward the oxygen, but they're still shared.

A covalent bond like those found in H2O means using a shared pair of electrons to form a bond.

OT: I'd recommend just getting a basic book on the subject or reading up a fair amount. Speaking as someone on a chemistry course at University, I'd say there's a lot more information needed than what can be typed in a forum post.

 

[Esotera]

It sort of depends on how indepth you want to get...from what you've said, it sounds like you want an understanding up to around an A-Level standard. I'd recommend reading through chemguide.co.uk and going through all the materials - if you really want to understand it, it'll take a fair amount of time.

As general advice, chemistry is the study of how electrons are shared between atoms, and the ability for this depends on the property of each nucleus.

 

[Albino Boo]

H20 comes about because hydrogen is more stable with no electrons and oxygen is more stable with those 2 added electrons.

You mean each hydrogen atom is more stable with 2 electrons than 1? The electrons from the hydrogen aren't given to the oxygen, they are shared with it. Oxygen is happy with a full 6 electrons in its p-orbital, and hydrogen is happy with a full 2 electrons in its s-orbital, so by sharing the electrons it means that both atoms are happy. Sure, the hydrogens become slightly-positive as its electrons are pulled toward the oxygen, but they're still shared.

A covalent bond like those found in H2O means using a shared pair of electrons to form a bond.

OT: I'd recommend just getting a basic book on the subject or reading up a fair amount. Speaking as someone on a chemistry course at University, I'd say there's a lot more information needed than what can be typed in a forum post.

No I mean the energy state of 1s0 is lower marginally than the 1s2. The electrons in the covalent bonds spends more time at the oxygen end of the orbit rather than the hydrogen end. The average effect is that the hydrogen spends more in the 1s0 energy state and the oxygen spends more time in the 2p6 state. This why you get the δ+ on the hydrogen and the δ- on the oxygen. Anyway that is what I was taught the best part of 20 years ago when I did my chemistry degree.

 

[BiscuitTrouser]

Heres my personal favourite example of why this doesnt work:

Invented by one of the greatest scientists ever but thats besides the point.

You see if a liquid is 40 degrees it might seem easy to declare "All atoms contain 40 degrees of energy yes! Or joules or what have you" but that isnt the case. Some atoms are moving VERY slowly by chance and some are moving MUCH faster than the "Average" 40 degree atom. So some might react and some might have so much energy it could react in a way others do not. Energy does not spread evenly and chemistry is not the slave of deterministic physics by our current models or on any level we predict.

The fact of the matter is that many MANY different charges and shapes can form a lot of different and interesting combinations. Isomerism are a good example of this if you fancy a quick google. The interaction in this way actually underpins the shape of ALL proteins that make life possible in their secondary and tertiary structure despite all being made of amino acids which contain the same few elements. Life is complicated. And life is chemistry. Ergo chemistry is complicated.

 

[Dryk]

Trust me, it's nowhere near as simple as you're assuming. Simulating what a single atom does as it goes about its day is well into "needs a supercomputer" territory. The underpinning equations are also incredibly complicated if you want to get down to the lowest possible level.

To get that lowest level knowledge you'll want to learn some quantum mechanics and then branch out from there.

 

[Altorin]

I've suddenly have a burning interest in understanding how chemistry works at the lowest possible level. Now, from what I understand, chemistry works based on how many protons/electrons atoms have vs. how many fit in the shell which determines how they connect to each. Theoretically speaking, if you know that, you know everything there is to know about how that atom works at a chemical level. Going from there, it should be possible to determine what will happen if you put a bunch of chemical X and chemical Y together just with pencil and paper or with a simulation. Now, I know there's temperature and stirring (giving the chemicals a greater surface area with one another) that have an impact, but it seems like it ought to be a simple thing to predict what will happen.

I've visited a few Chemistry websites, but they seem to fragment this questions into a whole array of different types of reactions. Oxidizations, Acids and Bases, Organic Chemistry, etc. It seems like there should to be a few general rules that underpin all this stuff. I get that combining H2 and O2 adds up to water, but I don't understand, from an electron basis, why the bonds holding those two chemicals together normally break to allow it when they are in each other's presence.

So what is it that I'm not getting here?

watch Crash Course Chemistry

it's ongoing, about 6 episodes out of a planned 40

http://www.youtube.com/watch?v=FSyAehMdpyI&list=PL8dPuuaLjXtPHzzYuWy6fYEaX9mQQ8oGr

And there are a few general rules that underpin all that stuff. One of them is called the Octet Rule. If you know how many electrons an element has, you can sort out what order those electrons are in, and then from there you can fairly easily predict the chemistry. That's what Chemistry is all about. It's an ongoing process though, and there are a lot of unanswered questions, but a lot of questions are already answered and have been for years.

 

[Wen-Chiao O'Boyle]

Hank Green(of vlogbrothers and VidCon fame) is currently creating a "Crash Course" series on the basics of Chemistry.
Here's a place to get started.

 

[thiosk]

As already mentioned, chemistry isn't quite as simple as that. However, of the physical sciences, chemistry is easily the most artistic. I can intuitively grasp the function of atoms without knowledge of what they are made of. In much the same way that an artist knows blending blue and yellow yields green, I know that I can bring silver together with sulfur to yield a new combination. And just as the artist can blend many different shades, I can guide and and direct atoms and molecules into new constructs that have never been seen before.

At the early stages, yeah, its a lot of memorizing solubility tables and molecular geometries-- octet rules, electron configurations, enthalpies and entropies with Gibbs and his free energies. Later, you see the the music in it.

 

[Veylon]

All right. I thank all of you for offering your answers. I can see know that I only have the barest grasp on my own ignorance. And apparently Quantum Mechanics come into play? Well, I guess there are deeper forces afoot than mere electrons. I was really hoping that some Grand Unified Theory of Chemistry existed that would bring together all the bits and pieces of Chemistry together into one chunk.

I don't mind be laughed at here; I'm asking a painfully stupid question from the standpoint of pitiable ignorance. I'll bookmark this thread and use the helpful resources that you all have provided. Chemistry's kind of been a blind spot in my knowledge of science and getting to know it better would be great.

Thank you so much.

 

[dvd_72]

Right, to put it simply all things in the universe are trying to enter the most stable state they can be in. Often, this means being in the lowest energy state that the energy it has will allow it to.

In chemistry atoms bond to lower their individual energy and become as stable as they can be. When the bonds in H2 and O2 break to make H2O they do so because the H2O is more stable than the H2 and O2 seperatly. It's simply a matter of atoms searching for a stable state.

Then you have to take into account activation energy. H2 and O2 will not spontaneously combine at STP (Standard Temperature and Pressure) because in order for the bonds in H2 and O2 to break they need to recieve a little bit of energy. The forming of the bonds in H2O from the now free H and O particles releases enough energy to break the bonds of several more H2 and O2 molecules and so forth, giving you the explosion associated with igniting hydrogen gas.

I apologize to those who actually do chemistry, I'm saying what I remember from IB chemistry and this may be over-simplified or even plain wrong.

 

[xXGeckoXx]

Right, to put it simply all things in the universe are trying to enter the most stable state they can be in. Often, this means being in the lowest energy state that the energy it has will allow it to.

In chemistry atoms bond to lower their individual energy and become as stable as they can be. When the bonds in H2 and O2 break to make H2O they do so because the H2O is more stable than the H2 and O2 seperatly. It's simply a matter of atoms searching for a stable state.

Then you have to take into account activation energy. H2 and O2 will not spontaneously combine at STP (Standard Temperature and Pressure) because in order for the bonds in H2 and O2 to break they need to recieve a little bit of energy. The forming of the bonds in H2O from the now free H and O particles releases enough energy to break the bonds of several more H2 and O2 molecules and so forth, giving you the explosion associated with igniting hydrogen gas.

I apologize to those who actually do chemistry, I'm saying what I remember from IB chemistry and this may be over-simplified or even plain wrong.

Your first sentence is pretty key. It is what I would use to layman explain most things. Why does H2O come about? It is more stable! Well then why does nitroglycerin come about then that is not stable? Because energy was put in, if you have energy you can make unstable things exist, stability is a measure of somethings ability to exist at a certain energy level!.