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Oh my. I had no idea of "pi-bonds basically occupy two side slots" or "uses up both mutually-perpendicular slots for the side bonds". This geometry aspect is co

Oh my. I had no idea of "pi-bonds basically occupy two side slots" or "uses up both mutually-perpendicular slots for the side bonds". This geometry aspect is completely new. I'll have a goggle but if you have any introductory resources for this, that would be very helpful. Books, sites, appropriate terms to search for I may not know, anything for a beginner just to get started, I'd appreciate it. Thanks.

logfromblammo 7y ago
Electrons around an atom occupy certain probability functions that correspond to the electron's energy level. The most basic and lowest energy of these at a given tier of orbital distance is nested spherical shells (s). Next is 3 different 2-lobed dumbbell shapes (p), oriented mutually perpendicularly (px, py, pz). The spherical mode (s) and the dumbbell-shaped modes (px, py, pz) can also hybridize when each has a single electron in it. Those hybrid modes can point lobes out in different directions. A stable mode can hold up to 2 electrons, each spinning in opposite directions. When an electron probability function of one atom overlaps with that of an adjacent atom, their functions can further hybridize into a bonding function. (They can also hybridize into anti-bonding functions, but ignore that for now.) When the bonding function puts the electron pair mostly along the line connecting the centers of the bound atoms, that's a sigma bond. It's the lowest-energy kind of bond, so it always (aka exceedingly rare exceptions) happens before any other kind of bond. In a carbon triple bond, the spherical orbital (s) will hybridize with just one of the dumbbell orbitals (p), forming one function (spx+) that mostly occupies one lobe of the former dumbbell, and one that mostly occupies the other (spx-). These two will then form direct sigma bonds with atoms on either side, separated by 180 degrees. That leaves the other two dumbbell modes (py, pz), mutually perpendicular to the two hybrids. Those can align with the parallel dumbbell modes of the adjacent atom and create bonding functions where the electron positions sort of average out to between the two bound atoms, but mostly occupy places that do not overlap with the sigma bond. Those are pi bonds. They happen between two aligned p orbitals. (There is another kind of indirect bond, a delta bond, that happens between two aligned d orbitals, which have more complex shapes. Those would be the fourth bond in a quadruple bond.) When those carbons are triple-bonded, their p-orbital atoms are leaning toward the adjacent bound atom. It's much harder for the atom on the opposite side to get their attention to maybe participate in a pi bond on that side. If you look at the bond through a microscope, you're just going to see a big blob of electron probability between the nuclei, with 6 electrons somewhere in it most of the time, where the triple bond is. It's not organized into discrete spaces for each separate bond. It only has separate slots when you look at the mathematical model. I don't have any specific resources, other than any modern chemistry textbook you can find. Possible search terms "electron orbitals", "bonding orbitals"
- tempguy9999 7y ago
  I do recognise spdf and the orbitals, I didn't realise the clouds interacted (well duh!), and that's the clearest description of pi and sigma bonds I've come across. That was brilliant, thanks!

logfromblammo 7y ago

Electrons around an atom occupy certain probability functions that correspond to the electron's energy level. The most basic and lowest energy of these at a given tier of orbital distance is nested spherical shells (s). Next is 3 different 2-lobed dumbbell shapes (p), oriented mutually perpendicularly (px, py, pz). The spherical mode (s) and the dumbbell-shaped modes (px, py, pz) can also hybridize when each has a single electron in it. Those hybrid modes can point lobes out in different directions. A stable mode can hold up to 2 electrons, each spinning in opposite directions. When an electron probability function of one atom overlaps with that of an adjacent atom, their functions can further hybridize into a bonding function. (They can also hybridize into anti-bonding functions, but ignore that for now.) When the bonding function puts the electron pair mostly along the line connecting the centers of the bound atoms, that's a sigma bond. It's the lowest-energy kind of bond, so it always (aka exceedingly rare exceptions) happens before any other kind of bond. In a carbon triple bond, the spherical orbital (s) will hybridize with just one of the dumbbell orbitals (p), forming one function (spx+) that mostly occupies one lobe of the former dumbbell, and one that mostly occupies the other (spx-). These two will then form direct sigma bonds with atoms on either side, separated by 180 degrees. That leaves the other two dumbbell modes (py, pz), mutually perpendicular to the two hybrids. Those can align with the parallel dumbbell modes of the adjacent atom and create bonding functions where the electron positions sort of average out to between the two bound atoms, but mostly occupy places that do not overlap with the sigma bond. Those are pi bonds. They happen between two aligned p orbitals. (There is another kind of indirect bond, a delta bond, that happens between two aligned d orbitals, which have more complex shapes. Those would be the fourth bond in a quadruple bond.) When those carbons are triple-bonded, their p-orbital atoms are leaning toward the adjacent bound atom. It's much harder for the atom on the opposite side to get their attention to maybe participate in a pi bond on that side. If you look at the bond through a microscope, you're just going to see a big blob of electron probability between the nuclei, with 6 electrons somewhere in it most of the time, where the triple bond is. It's not organized into discrete spaces for each separate bond. It only has separate slots when you look at the mathematical model. I don't have any specific resources, other than any modern chemistry textbook you can find. Possible search terms "electron orbitals", "bonding orbitals"

tempguy9999 7y ago
I do recognise spdf and the orbitals, I didn't realise the clouds interacted (well duh!), and that's the clearest description of pi and sigma bonds I've come across. That was brilliant, thanks!