can anyone explain what pi-bonding is? as far as i understand it has to do with electrons in d-orbitals, but that's about it.

Thanks for any help


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I don't think it has anything to do with any orbital.
Far as I know, it's when there is a double bond between two atoms, such as in alchenes.
CH2=CH2-CH3 the = is a pi bond the - is a sigma bond. pi bonds give way to additive reactions, and sigma bonds give way to substitution reactions.
sorry if my terms are off, I'm studying this in italian....

s, p, d, f (and g!) orbitals are *ATOMIC* orbitals.

sigma, pi (and delta!) orbitals are *MOLECULAR* orbitals. (like atomic orbitals, they can hold 2 electrons each, one spinning up, the other spin down)

Of course, you must bear in mind, that orbitals are just made up bits of mathematical trickery and any description of what they "are" should be taken with a pinch of NaCl and a raised eyebrow,
when chemical bonds form,
it's useful to think of the individual s and p (and d and f...) atomic orbitals doing a shimmery dance and morphing into nice new molecular orbitals of the chemical bond.

A "pi" bonding orbital is one where the electron density is mostly whizzing about in two lobes, one above and and one below the axis of the bond.
A "sigma" bonding orbital has electrons directly along the bond, on the line between the two nuclei.

Thus, using the very scientific "hot dog" theory of bonding, a sigma orbital is like a sausage, and a pi orbital is like a bread roll around it.

As for "why" they are these shapes,
well that's just the patterns you get,
when you have a pair of +ve nuceli trying to run away from each other like hell,
a load of whizzing electron pairs which all hate each other and want to be as far apart as possible, but also are hugely attracted to the +nuclei.
Frankly it's amazing they all manage to form bonds at all.

For pics representing orbitals try [url]http://www.shef.ac.uk/chemistry/orbitron/[/url] where you can see some animations that might help (or hinder) - including some p-orbitals "glooping" into pi orbitals.

rofl, way to go feline!

yup, I think the shape can be understood with schrodinger's equation which involves alot of very complicated uni-level maths. my teacher said she once had a genius student who was interested and so learned all the maths for it and then solved it. just so you know it's possible ^_~. btw, you can also have mixes of the sausage and the breadroll, I believe.

Is pi-bonding where two chicks in a sorority drink each other's beer?

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