Week 1 Flashcards
Molecules have a shape what type of shapes ?
Some simple molecules maybe linear (one-dimensional) or planar (two-dimensional). or three dimensional. most are three dimensional
what the ways to predict a shape?
Yes. For covalent compounds of the s-andp-blocks (including organic chemistry),we can use VSEPR.
for transition metals we can use d and f blocks
VSEPR
VSEPR stands for Valence Shell Electron Pair Repulsion. Sometimes referred to as VSEPR Theory.It is based on the assumption that electr on pairs repel each other.Only appropriate for s-and p-block compounds.
Note
Note that VSEPR is a simple model for predicting structures. It is not a good model for understanding electronic structure.
4 valence electrons
tetrahedral
109.5
3 valence electrons
trigonal planar
120
2 valence electrons
linear
180
tetrahedral chiral
when all four atoms around the carbon are different,VSEPR still predicts a tetrahedral structure but the molecule is now chiral.A chiral molecule comprises a pair of non-superimposable mirror images.MoreonthisfromJonathanClaydenlater.
tetrahedral chiral
when all four atoms around the carbon are different,VSEPR still predicts a tetrahedral structure but the molecule is now chiral.A chiral molecule comprises a pair of non-superimposable mirror images.
5 valence electron
1 lone pair of electrons
trigonal pyramidal
107
lone pair of electrons
lone pairs repel more than bond pairs because they are only associated with the central atom. The H–N–H angles are therefore less than 109.5° and are about 107°.
6 valence electrons
2 lone pairs
bent
104.5
6 valence electrons
octahedral
7 valence electron
one lone pair
square-based pyramid
8 valence electrons
two lone pairs
square planar
