Electron energy: forever?

[Mellinia]

If electrons have wave and particle like properties, wouldn't it be a form of energy? electric, perhaps? But it has mass, why?? Does light have mass?

[swansont]

If electrons have wave and particle like properties, wouldn't it be a form of energy? electric, perhaps? But it has mass, why?? Does light have mass?

 

Electrons have energy. There's mass energy, and kinetic energy from its motion. Why it has mass is an open question. Photons do not have mass.

[lemur]

A high-energy photon will result in ionization if the interaction includes the electron.

Meaning the photon energy knocks one or more electrons off the atom? How do atoms get negatively ionized, actually, since that requires them gaining electrons, right? How does energy cause a particle to attract extra electrons?

 

"Going around" is also gives a false impression. In an S orbital (that's the term for them), there is zero angular momentum. There's no analogy to a classical "going around" at all.

Yes, s/p/etc. orbitals. I vaguely remember the letters after reading a book recently but I do recall that the number of electrons per orbit is 2p^2 (2,8,18,32). Do I get extra credit for that?

 

I didn't know that "angular momentum" of electrons referred to their "going around the nucleus." I didn't get that but I thought it meant something else. But if it's not a "standing wave," meaning it doesn't stand still AND it's not going around (i.e. orbiting), what is it doing exactly?

[mississippichem]

Meaning the photon energy knocks one or more electrons off the atom? How do atoms get negatively ionized, actually, since that requires them gaining electrons, right? How does energy cause a particle to attract extra electrons?

 

Sort of. I would prefer to say that the photon transfers to the electron sufficient energy to exceed the ionization energy requirement for that electron. I don't know how far the knocking analogy goes.

 

Atoms become anions [negatively charged] because full orbitals are lower in energy than "close-to-full" orbitals. For example Fluorine lacks one electron from having a complete [math] 2p^{6} [/math] subshell. It is energetically more favorable to take on a -1 negative charge than not in this case. Empty orbitals and half-filled orbital sets tend to be favored as well.

 

 

Yes, s/p/etc. orbitals. I vaguely remember the letters after reading a book recently but I do recall that the number of electrons per orbit is 2p^2 (2,8,18,32). Do I get extra credit for that?

 

I didn't know that "angular momentum" of electrons referred to their "going around the nucleus." I didn't get that but I thought it meant something else. But if it's not a "standing wave," meaning it doesn't stand still AND it's not going around (i.e. orbiting), what is it doing exactly?

 

There is really no sound analogy with the classical world. A classical body's angular momentum is given by [math]\vec{r} \times m\vec{v}[/math]. In quantum mechanics angular momentum is an operator on a wave function serving to define the shape of that wave function. So we use the quantum number [math] \ell [/math] to talk about the angular momentum of electrons in atoms. For an s-orbital in a hydrogen like atom [math] \ell=0 [/math]. For a p-orbital, [math] \ell=1[/math] and so on. The derivation of "[math] \ell [/math]" is somewhat complicated.

Edited January 25, 2011 by mississippichem

[lemur]

Sort of. I would prefer to say that the photon transfers to the electron sufficient energy to exceed the ionization energy requirement for that electron. I don't know how far the knocking analogy goes.

So you don't want to attempt to make a classical mechanical model? How else do you theorize what is actually going on that causes these numbers and observations to occur?

 

Atoms become anions [negatively charged] because full orbitals are lower in energy than "close-to-full" orbitals. For example Fluorine lacks one electron from having a complete [math] 2p^{6} [/math] subshell. It is energetically more favorable to take on a -1 negative charge than not in this case. Empty orbitals and half-filled orbital sets tend to be favored as well.

I understand that shells can come close to fullness and thus be positively charged relative to the full shell. What I don't understand is how adding energy causes that; unless it somehow "knocks free" one or more of the electrons in a full shell. (but there's more pesky classical mechanical modeling for you - how else do you explain force interactions logically except with classical mechanics? Aren't they just arbitrary interactions otherwise? It would be like saying that person A pushed person B and person B fell but the two events had nothing to do with the pushing itself, i.e. pushing-action 1 resulted in falling-state 1 and then finding an equation to elegantly describe all possible ratios of pushing actions and falling-states. You would never truly understand how pushing causes falling.

 

There is really no sound analogy with the classical world. A classical body's angular momentum is given by [math]\vec{r} \times m\vec{v}[/math]. In quantum mechanics there is a similar situation, but that angular momentum is an operator on a wave function serving to define the shape of that wave function.

Again, don't you want to know HOW angular momentum causes the wave-function shape to change and why?

 

 

 

[steevey]

Well, the observed color of the emission that follows the nucleus becoming excited would probably be "gamma-colored" i.e. a much higher frequency of light than humans [or any other creatures for that matter I safely assume] can see. Nuclear transitions are really high energy when compared the electron transitions which corresponds to much higher frequencies.

 

Does the mass (or amount of neutrons and photons) of the nucleus effect the photon emitted? Or does the photon hit an individual particle in which case whats the difference between the photon hitting the neutron or proton of the nucleus?

Edited January 26, 2011 by steevey

[swansont]

Meaning the photon energy knocks one or more electrons off the atom? How do atoms get negatively ionized, actually, since that requires them gaining electrons, right? How does energy cause a particle to attract extra electrons?

 

Energy doesn't cause a particle to attract extra electrons. That's a force, and energy isn't force. Electrons "shield" the nucleus; from far away we see them as neutral, but the shielding is not complete, so close up you can still have a net attractive force, and an additional electron can become bound. The ease by which this happens depends on the electron configuration.

 

 

I didn't know that "angular momentum" of electrons referred to their "going around the nucleus." I didn't get that but I thought it meant something else. But if it's not a "standing wave," meaning it doesn't stand still AND it's not going around (i.e. orbiting), what is it doing exactly?

 

Angular momentum is classically the tendency to rotate or revolve about an axis, just as linear momentum tells you the tendency to go in a straight line.

 

You can't tell what an electron is doing when it's not being measured.

[lemur]

Energy doesn't cause a particle to attract extra electrons. That's a force, and energy isn't force. Electrons "shield" the nucleus; from far away we see them as neutral, but the shielding is not complete, so close up you can still have a net attractive force, and an additional electron can become bound. The ease by which this happens depends on the electron configuration.

Right, but what does adding energy to the atom do that "ripens" it for additional electron-binding?

 

Angular momentum is classically the tendency to rotate or revolve about an axis, just as linear momentum tells you the tendency to go in a straight line.

Yes, I think of a rotating object but this seems slightly different to me than something in orbit, probably just a subjective bias but in my mechanical thinking a satellite in orbit is on a geodesic path and a thing rotating is not in linear motion.

 

You can't tell what an electron is doing when it's not being measured.

You can't really tell what anything is doing when it's not being observed (and I admire the empirical rigor of recognizing that something is ultimately unknowable when not directly observed); however, you can create models of what you think it may be doing based on knowledge derived from observations. It's like if you see a mole popping up in different places in your garden, you can theorize that their may be tunnels under the ground between the holes, even if you can't directly see the tunnels. You can even theorize about how the mole digs the tunnels, what it does with the dirt as it goes, etc. Did Einstein discover gravity's effect on light by watching stars or did he first theorize and thereafter test the implications of the theory? It seems like you eschew pro-active modeling and deductive testing/observation/reasoning for some reason and I'm not sure why you would unless you think science would just be better if it stuck with describing patterns of observations/measurements without ever trying to create explanatory models for how and why things behave as they do.

 

 

 

[swansont]

Right, but what does adding energy to the atom do that "ripens" it for additional electron-binding?

 

It doesn't.

 

You can't really tell what anything is doing when it's not being observed (and I admire the empirical rigor of recognizing that something is ultimately unknowable when not directly observed); however, you can create models of what you think it may be doing based on knowledge derived from observations. It's like if you see a mole popping up in different places in your garden, you can theorize that their may be tunnels under the ground between the holes, even if you can't directly see the tunnels. You can even theorize about how the mole digs the tunnels, what it does with the dirt as it goes, etc. Did Einstein discover gravity's effect on light by watching stars or did he first theorize and thereafter test the implications of the theory? It seems like you eschew pro-active modeling and deductive testing/observation/reasoning for some reason and I'm not sure why you would unless you think science would just be better if it stuck with describing patterns of observations/measurements without ever trying to create explanatory models for how and why things behave as they do.

 

I eschew attempts that are contrary to empirical evidence and models that are untestable.

[lemur]

It doesn't.

Then how does adding energy to an atom cause it to lose an electron?

 

I eschew attempts that are contrary to empirical evidence and models that are untestable.

What do you mean by "contrary to empirical evidence" then? That sounds like it could have a lot of subjective bias. As far as being testable, do you mean something more than consistently agreeing with observations? Theories should be deducible to testable/falsifiable propositions but that doesn't mean they have to be directly observable, does it? E.g. Paleontology can theorize about dinosaur behavior based on fossil evidence without being able to test their theories on living dinosaurs. Still, they attempt to falsify their theories by interpreting existing evidence and seeking new information.

 

 

[swansont]

Then how does adding energy to an atom cause it to lose an electron?

 

An electron is bound to an atom. Adding enough energy frees it — the kinetic energy is larger in magnitude than the kinetic energy.

 

What do you mean by "contrary to empirical evidence" then? That sounds like it could have a lot of subjective bias.

 

That's why you want to use math, so that the model makes specific predictions, and then there is no subjective bias.

 

As far as being testable, do you mean something more than consistently agreeing with observations? Theories should be deducible to testable/falsifiable propositions but that doesn't mean they have to be directly observable, does it? E.g. Paleontology can theorize about dinosaur behavior based on fossil evidence without being able to test their theories on living dinosaurs. Still, they attempt to falsify their theories by interpreting existing evidence and seeking new information.

 

You test it on other evidence. In this case, other fossils.

[lemur]

An electron is bound to an atom. Adding enough energy frees it — the kinetic energy is larger in magnitude than the kinetic energy.

Sorry, I posted the wrong question. I meant to ask how adding energy to an atom causes it to gain an electron.

 

That's why you want to use math, so that the model makes specific predictions, and then there is no subjective bias.

But math doesn't do anything more than relate measurements according to predictive patterns/correlations. Theoretical models are needs that explain how the actual physical processes work that cause the math to work the way it does.

 

You test it on other evidence. In this case, other fossils.

Right, so you can generate models of physical processes that are too small to observe directly and then test the models against various evidence and logic, right?

 

 

[swansont]

Sorry, I posted the wrong question. I meant to ask how adding energy to an atom causes it to gain an electron.

 

It doesn't.

 

But math doesn't do anything more than relate measurements according to predictive patterns/correlations. Theoretical models are needs that explain how the actual physical processes work that cause the math to work the way it does.

 

Relating measurements to predictions is pretty powerful. Unless you can test the model, you don't know if it's right.

 

Right, so you can generate models of physical processes that are too small to observe directly and then test the models against various evidence and logic, right?

 

Right.

[mississippichem]

But math doesn't do anything more than relate measurements according to predictive patterns/correlations. Theoretical models are needs that explain how the actual physical processes work that cause the math to work the way it does.

 

The theoretical model and "mental picture" of a theory come from the math. The math describes the observed events precisely. But no prose or conceptual language can describe a theory as well and unambiguously as the math can.

[steevey]

The theoretical model and "mental picture" of a theory come from the math. The math describes the observed events precisely. But no prose or conceptual language can describe a theory as well and unambiguously as the math can.

 

I might have to disagree since if you just reason something out you can come up with an equally valid solution. If I want to...find the area of an annulus, thats like PiR^2-Pir^2, but in reasoning, I could say thats "Big circle minus the little circle".

 

The universe doesn't even work like that mathematically, there's nothing about the universe saying theres a radius and pi, its that some atoms got moved away from an object, and then math based on that observation allows us to describe it much faster without working it out other ways. All the physics to describe something are there, but since we don't know all of them, we use the logical system of mathematics to take a shortcut.

 

This is even true for simple math. Never in reality are two apples going "1+1=2". It just happens to be that one apple is getting close to other apple. They never count as the same system. You could even try it for yourself. What happens when you bring two apples close together? Do they fuse to make one apple with twice as much material as either of the individual apples? Nope, the electro-magnetic force doesn't even allow the surface of the apples to actually make contact, only seem like it on a large scale. Not only that, both the apples have different masses anyway.

Edited January 27, 2011 by steevey

[lemur]

It doesn't.

Then how does an atom become negatively ionized? Only when a partially-filled shell loses electrons and becomes even less filled?

 

Relating measurements to predictions is pretty powerful. Unless you can test the model, you don't know if it's right.

Getting it right is not as important as being rigorous in the process of model-building and testing through logical comparison of observed data. The Bohr model was good theorizing because it fit the known data and was rigorously critically tested until its weaknesses were found. This made it part of a constructive scientific process. More such mechanical models need to be contructed and subject to critical rigor, imo, in hopes of finding a model that explains and predicts physical behavior at that level in terms of the mechanics of how/why things act as they do. Why should it be simply assumed that sub-atomic particles are simply fundamentally incomprehensible in qualitative terms?

 

The theoretical model and "mental picture" of a theory come from the math. The math describes the observed events precisely. But no prose or conceptual language can describe a theory as well and unambiguously as the math can.

Math always wins the battle for accuracy. But I don't understand how people can think that a perfectly accurate equation is an adequate substitute for understanding/modeling how the reality being measured and predicted actually works. What if you explained how an incadescent lightbulb works by giving the equation for resistance of the filament relative to the luminosity of the glow? Yes, you would accurately predict how bring the lightbulb would shine at each level of current passing through the filament, but how would you ask further questions such as whether the type of conductor/resistor used matters, why some lightbulbs produce more heat and less light, etc. You wouldn't even understand HOW the electricity causes the filament to glow. All these kinds of questions require qualitative mechanics beyond the equations, no?

[steevey]

Then how does an atom become negatively ionized? Only when a partially-filled shell loses electrons and becomes even less filled?

 

The opposite. When an atom GAINS an electron, then there are more electrons than protons, giving the atom a negative charge since electrons have a negative charge. Alternatively, if an atom lost an electron, there would be more protons than electrons, giving the atom a positive charge.

 

Say I have Sodium. Now, I take that sodium and combine it with chlorine. The sodium atom has lost an electron to the chlorine, so now the sodium atom has more protons (from the nucleus) than electrons, while the chlorine gained an electron making it positive and then forming salt since opposite charges attract.

Edited January 27, 2011 by steevey

[lemur]

The opposite. When an atom GAINS an electron, then there are more electrons than protons, giving the atom a negative charge.

 

Right, but I meant how does energy cause an atom to gain an electron to become negatively ionized? OR, I asked, does it start with a partially filled shell (e.g. three electrons in the second orbit) and then lose one? That wouldn't seem to be possible, though, since I don't see why an atom with a partially-filled shell would be floating around unattached anyway. I think it would already be an ion. I guess it would get that way by energy breaking apart a molecule into components, of which some would be positively charged and others negative. Did I just answer my own question? Is there some other way for an atom to gain an electron by adding energy?

[steevey]

Right, but I meant how does energy cause an atom to gain an electron to become negatively ionized? OR, I asked, does it start with a partially filled shell (e.g. three electrons in the second orbit) and then lose one? That wouldn't seem to be possible, though, since I don't see why an atom with a partially-filled shell would be floating around unattached anyway. I think it would already be an ion. I guess it would get that way by energy breaking apart a molecule into components, of which some would be positively charged and others negative. Did I just answer my own question? Is there some other way for an atom to gain an electron by adding energy?

 

Ok, if you have an element such as Fluorine, its missing 1 electron in its outer shell to be completely stable (or to have 8 electrons in an outer shell). However, because of the properties of matter, an un-ionized atom of fluorine STILL only has as many protons as there are electrons even though theres an outer electron missing to make the element stable. So, when fluorine DOES gain an electron and gets its outer shell filled, it then has more electrons than protons, making it a negative ion.

[lemur]

Ok, if you have an element such as Fluorine, its missing 1 electron in its outer shell to be completely stable (or to have 8 electrons in an outer shell). However, because of the properties of matter, an un-ionized atom of fluorine STILL only has as many protons as there are electrons even though theres an outer electron missing to make the element stable. So, when fluorine DOES gain an electron and gets its outer shell filled, it then has more electrons than protons, making it a negative ion.

 

That makes sense. I hadn't thought of that, though I probably could have. So then how can energy cause a flourine atom to ionize negatively? Would it then behave as stable because its outer shell was filled yet be attracted to positive ions to stabilize/neutralize its charge?

[steevey]

That makes sense. I hadn't thought of that, though I probably could have. So then how can energy cause a fluorine atom to ionize negatively? Would it then behave as stable because its outer shell was filled yet be attracted to positive ions to stabilize/neutralize its charge?

 

When Fluorine gains a single electron it becomes both stable and negatively ionized. The reason energy comes into play is I guess because if you didn't have that extra energy, there wouldn't be enough electro-magnetic force generated by an opposing atom without it to cause the electrons to want to bond.

 

Like, if I have oxygen and carbon, they both want electrons from each other, but their nuclei are so powerful that the attraction of either nuclei cannot overcome the other. But, when I shoot a photon at an electron in the highest energy state, the electron then has enough energy to "leap further" from its parent nucleus so that the charge of the parent nucleus isn't as strong at that greater distance, which leaves room for the other atom to also be attracted to it, but not steal it since the parent nuclei is still fairly attractive, forming a covalent bond. Actually, I might be thinking of how water works, but I know many compounds work this way.

 

In other words, with energy, electrons can break "more free" from their parent nucleus since the electromagnetic force gets weaker by the square of the distance. Adding energy to a bound electron increases its distance from the nucleus, thus weakening the effect the electro-magnetic force that the parent particle has on it. That's why outer electrons in heavy elements such as uranium can be put into another bond more easily than something such as oxygen, however, as a consequence of that property, the bond itself wouldn't store as much energy which is why organisms typically don't have enzymes and chemicals containing metals with high atomic numbers.

Edited January 27, 2011 by steevey

[lemur]

When Fluorine gains a single electron it becomes both stable and positively ionized. The reason energy comes into play is I guess because if you didn't have that extra energy, there wouldn't be enough electro-magnetic force generated by an opposing atom without it to cause the electrons to want to bond.

 

Like, if I have oxygen and carbon, they both want electrons, but their nuclei are so powerful that the attraction of either nuclei cannot overcome the other. But, when I shoot a photon at an electron in the highest energy state, the electron then has enough energy to "leap further" from its parent nucleus so that the charge of the parent nucleus isn't as strong at that greater distance, which leaves room for the other atom to also be attracted to it, but not steal it since the parent nuclei is still fairly attractive, forming a covalent bond.

 

In other words, with energy, electrons can break "more free" from their parent nucleus since the electromagnetic force gets weaker by the square of the distance. Adding energy to a bound electron increases its distance from the nucleus, thus weakening the effect the electro-magnetic force that the parent particle has on it.

 

So photons raise the energy level of the electrons in the outer shell to further distances from the nucleus - and this allows other atoms to bond with the positive charge that is left unbalanced by the electron moving further away? This sounds similar to the process of photon emission. What causes the atom to emit a photon or not before some other atom bonds with it in its energized state? Is it when the electron energy somehow decreases enough that the EM force of the protons "reel it in" to a lower level/state? Would it then be the proximity of the available electron from another atom being closer to the nucleus than the excited electron that causes it to get "reeled in" instead of its own electron?

[steevey]

So photons raise the energy level of the electrons in the outer shell to further distances from the nucleus - and this allows other atoms to bond with the positive charge that is left unbalanced by the electron moving further away?

Well, sometimes bonds don't need any extra energy from fire or light. Room temperature might be good enough for them.

 

 

 

This sounds similar to the process of photon emission. What causes the atom to emit a photon or not before some other atom bonds with it in its energized state?

Generally, an "electron" emits a photon when it travels to a *lower* energy state from a higher one, or when it is accelerated. Otherwise, I don't know for sure. I think the reason that in something like a covalent bond why an electron wouldn't be emitting light is either because its not changing energy levels like with multiple atoms of the same element like carbon, or that maybe the electron actually IS gaining and losing energy when it switches off from one atom to another. You should probably ask swan or some other expert.

 

 

Is it when the electron energy somehow decreases enough that the EM force of the protons "reel it in" to a lower level/state? Would it then be the proximity of the available electron from another atom being closer to the nucleus than the excited electron that causes it to get "reeled in" instead of its own electron?

 

The energy of an electron at least according to my understanding doesn't decrease *until* the electron jumps down to a lower energy state. I'm guessing that if an outside force isn't strong enough, an electron can as you say gets "reeled in" to a lower energy state after it receives a proton, thus emitting an photon.

 

 

But like I said before, you should probably check with some expert, because I can't remember exactly how it works.

 

Also, I said fluorine becomes "positively ionized" even though what I meant to type was "negatively ionized"

Edited January 27, 2011 by steevey

[swansont]

Then how does an atom become negatively ionized? Only when a partially-filled shell loses electrons and becomes even less filled?

 

I explained this already

http://www.scienceforums.net/topic/54262-electron-energy-forever/page__st__20__p__585639#entry585639

 

Getting it right is not as important as being rigorous in the process of model-building and testing through logical comparison of observed data. The Bohr model was good theorizing because it fit the known data and was rigorously critically tested until its weaknesses were found. This made it part of a constructive scientific process. More such mechanical models need to be contructed and subject to critical rigor, imo, in hopes of finding a model that explains and predicts physical behavior at that level in terms of the mechanics of how/why things act as they do. Why should it be simply assumed that sub-atomic particles are simply fundamentally incomprehensible in qualitative terms?

 

The Bohr model was abandoned because it didn't fit the known data. It was "good theorizing" because it started with valid physics concepts, added an hypothesis which didn't contradict empirical evidence, and went through the right process on its way to being rejected.

 

I'm not sure who you think is assuming that sub-atomic particles are fundamentally incomprehensible. People wouldn't do science of they thought things were fundamentally incomprehensible. That's very different from pointing out that a particular model fails to work.

 

Math always wins the battle for accuracy. But I don't understand how people can think that a perfectly accurate equation is an adequate substitute for understanding/modeling how the reality being measured and predicted actually works. What if you explained how an incadescent lightbulb works by giving the equation for resistance of the filament relative to the luminosity of the glow? Yes, you would accurately predict how bring the lightbulb would shine at each level of current passing through the filament, but how would you ask further questions such as whether the type of conductor/resistor used matters, why some lightbulbs produce more heat and less light, etc. You wouldn't even understand HOW the electricity causes the filament to glow. All these kinds of questions require qualitative mechanics beyond the equations, no?

 

The problem is when you get to questions of "how this works" where there is no testable model. Those questions can't be answered, because there's no way to tell if they are wrong.

[steevey]

I explained this already

http://www.sciencefo...639#entry585639

 

 

 

The Bohr model was abandoned because it didn't fit the known data. It was "good theorizing" because it started with valid physics concepts, added an hypothesis which didn't contradict empirical evidence, and went through the right process on its way to being rejected.

 

I'm not sure who you think is assuming that sub-atomic particles are fundamentally incomprehensible. People wouldn't do science of they thought things were fundamentally incomprehensible. That's very different from pointing out that a particular model fails to work.

 

 

 

The problem is when you get to questions of "how this works" where there is no testable model. Those questions can't be answered, because there's no way to tell if they are wrong.

 

 

 

So I take it there wasn't any flaws in what I was saying?