[SapereAude1490]

So I found this somewhere

"Electrons in zones close to the center are lower in energy than electrons in zones at greater distances from the center. "

What kind of energy are we talking about here? Kinetic? Potential?

If you're closer to the nucleus, shouldn't energy be higher? The electric force is, according to Coulomb's law. How come the further away from the nucleus the electron is, the higher it's energy? What am I missing here? Am I stupid? 

[fledarmus]

I think this is talking about ionization energy - the closer the electron is to the nucleus, the more energy will be required to remove it from the atom.

[SapereAude1490]

As a matter of fact, I was looking at ionization energies of the 2nd row elements and trying to figure out why Be and N have higher ionization energy than B and O respectively.

The explanation for the Be and B difference is in the electron configurations: Be 1s2 2s2,  B 1s2 2s2 2p1

The 2p orbital has a bit higher energy than 2s orbital, and less energy is required to take away that electron and ionize boron. Also, my textbook (and a quick google search) tells me that 2s2 is somehow stable because of "quantum mechanical" reasons. No specifics, just that.

As for N and O we have these: N 1s2 2s2 2p3   and   O 1s2 2s2 2p4

with N          

and O           

The textbook is a bit useless here, but I found somewhere that that extra electron that's paired up in the p orbital is repulsed by others and the raise in the nucleus charge can't compensate that somehow.


Now, you say that the closer the electron to the nucleus, the harder it is to remove it - that makes perfect sense; no other electrons to repulse it, and the closer to the core, the stronger the attraction.

But what does it mean when they say that 1s1 electron has the lowest energy state? You need more energy to remove it than an electron in a f orbital and that same electron is in a higher energy state?

Higher energy state = more energy to remove it? Do you see what's so confusing? more energy=less energy - HOW?

Can someone help disentangle me from this semantic web that I have fallen victim to? Please? 

[antimatter101]

Well I can untie your knots.
An electron with a low speed (lower energy) is attracted to a nucleus and because its velocity is low it is attracted closer to the nucleus. An electron with a high velocity is attracted to a nucleus and because its velocity is high it is momentum nearly overcomes the electromagnetic attraction, resulting in a higher orbital.
Actually velocity is not the word that accurately describes that property, but you get it.
In order to drop down to lower energies the electron will emit electromagnetic radiation (light). Some materials when they have electrons excited the electron retains that energy for some time before it can release it. That gives rise to fluorescent material.

[SapereAude1490]

So, the farther away from the core the electron is, the higher its velocity(ish), and the energy is higher too (kinetic? mv²/2)

That actually makes perfect sense. I think I just got lost with all these atom models that I've been reviewing.

Thank you.

[Borek]

It doesn't want to be that easy.

Electron in the atom (or molecule) doesn't behave like a particle, so it is not possible to assign it a velocity.

[SapereAude1490]

Well, I did say velocity(ish)   

[Enthalpy]

Not only is there no velocity, but electrons with zero momentum can be on outer shells like 4s.

Kinetic energy does exist but is related to how fast the wave function varies over position, including in its phase.

Why "so many atom models"? Quantum Mechanics works precisely, other theories don't, so don't waste your time.

Excellent visual help there
http://winter.group.shef.ac.uk/orbitron/
Choose an orbital at the left. Colours show alternating sign of the wave function, since this website takes the solution sets with phase 0° and 180°.

-----

Two electrons on the same 2p are geometrically nearer to an other than on distinct 2p and repel an other more strongly, that's why they first occupy distinct orbitals provided these are equivalent.

I understand that way the lower ionization energy of oxygen.

Generally (probably not the case here) remember that individual atoms are an exception. They use to go in molecules, and then the ionization energy is completely different.

[SapereAude1490]

I should look at electrons as 3D de Broglie waves and ignore the Bohr and other models? Well, OK.

And thank you for the Oxygen explanation.

[Enthalpy]

If it's atomic oxygen, this is the way I understand it.
If it's molecular, the explanation is completely different, with two electrons on anti-binding molecular orbitals, whereas the nitrogen molecule has only binding orbitals, all filled.

The Bohr atom is not false! "Energy levels" is just less detailed than "wave function having that mathematical expression", it's less justified as well, and doesn't make accurate predictions like forbidden transitions. In constrast, by just telling Schrödinger's equation which isn't limited to atoms, QM can deduce very precisely all orbitals and all possible transitions, magnetic moments - basically everything. Bohr's atom is the roller skate and QM the Rolls.