Chapter 9 Flashcards
What are bond angles?
angles made by the lines joining the nuclei of atoms
What 2 things determine the size and shape of the molecule?
bond angles and bond lengths
What is a tetrahedral?
4 corners, 4 faces, each an equilateral triangle
What is a bent shape?
if atom A lies above 2 atom Bs
What is a trigonal planar?
if atom A is on the same plane as atom Bs
What is a trigonal pyrimidal?
if atom A lies above the plane of 3 atom Bs
What are the 5 basic molecular arrangement shapes?
linear AB2 | trigonal pyramidal AB3 | tetrahedral AB4 | trigonal bipyramidal AB5 | octahedral AB6
What does VESPR stand for?
valence shell electron pair
What is the VESPR model?
based on the idea that electron domains are negatively charged and repel one another
What is an electron domain?
a region in which the bonding-pair electrons are found
What is the best arrangement of a given number of electron domains?
one that minimizes the repulsions among them
What is electron domain geometry?
arrangement of electron domains about the central atom of an ABn molecule/ion (includes lone pairs)
What is molecular geometry?
an arrangement of the atoms
How can we determine the molecular geometry?
based on how many electron domains there are due to bonds
What is the effect of non-bonding electrons on bond angles?
exert a greater repulsive force on neighboring electron domains = compress (decrease) bond angles
What is the effect of multiple bonds on bond angles?
multiple bonds = larger electron domains = exert greater repulsive force on neighboring electron domains
What is the most stable 5 electron domain shape and why?
trigonal bipyramidal due to less repulsion
What is the most stable 6 electron domain shape and why?
octahedron, all angles are 90
How are the shapes of larger molecules determined?
determine VESPR shape of each central atom
What does the dipole moment depend on for molecules with 2< atoms?
both the polarities of the individual bonds and the geometry of the molecule
What indicates if a molecule with 2< atoms is nonpolar?
dipole vectors point at OPPOSITE directions
What indicates if a molecule with 2< atoms is polar?
dipole vectors point at the SAME direction
What is the valence bind theory?
bonding electron pairs are concentrated in the regions between atoms | nonbonding e- pairs lie in regions in space
What is Lewis’s theory?
covalent bonding happens due to the concentration of electron density between 2 nuclei from the atoms sharing electrons
What is the optimum distance between 2 nuclei in a covalent bond?
when the attractive forces between opposite charges are balanced by the repulsive forces between like charges
