VSEPR Formula?

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Jasmine Wu 1L
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VSEPR Formula?

Postby Jasmine Wu 1L » Sun Nov 05, 2017 10:57 pm

What does it mean when a question asks for a VSEPR formula and the hybridization of the central atom? Would it be the same thing as the VSEPR models Dr. Lavelle drew in class?

Thanks :)

sofiakavanaugh
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Re: VSEPR Formula?

Postby sofiakavanaugh » Sun Nov 05, 2017 11:26 pm

I'm not sure about the equation, but hybridization isn't something we have learned yet. I think we will probably get to it soon because its related to what we have been talking about with expanded octets, electron configurations, and orbitals but we haven't covered it in lecture yet.

Andrew Nguyen 2I
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Re: VSEPR Formula?

Postby Andrew Nguyen 2I » Mon Nov 06, 2017 2:36 pm

The VSEPR formula is denoted as AXE where X may have "A" represents the central atom (you write it as A) and X may have a subscript with a number to represent the number of bonded atoms are bonded to the central atom; if it is 1, then it is simply written as X with no subscript. E would be written the same as X, but the subscript represents the number of lone pairs around the central atom. So CN- would be an example of a molecule with the formula "AXE".

The hybridization of an atom refers to the concept of mixing the previous spdf orbitals into new "hybrid" orbitals; the process is much more detailed, though to determine the hybridization of a orbital you count how many lone pairs the relevant atom has around it along with the number of atoms bonded to it. Add these two numbers for what is called the steric number. If the steric number is 3 for example the hybridization will be sp2 (superscript for the numbers); if the steric number is 4 it will be sp3; if the steric number is 5 it will be sp3d - essentially you start with s and then p and then d, and so forth if needed (the maximum subscript on the subshell letter depends on how many orbitals the subshell can hold, p would stop at 3).
Last edited by Andrew Nguyen 2I on Mon Nov 06, 2017 2:39 pm, edited 1 time in total.

Julie Steklof 1A
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Re: VSEPR Formula?

Postby Julie Steklof 1A » Mon Nov 06, 2017 2:36 pm

VSEPR formulas are generalized formulas describing the molecular shape of a compound. A represents the central atom, X represents the bonded atom(s), and E represents the lone pair(s) of a molecule. For example, a trigonal pyramidal molecule would have the VSEPR formula: AX3E, one central atom bonded to 3 atoms with one lone pair of electrons.


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