Molecular Geometry Flashcards
What does VSEPR stand for
Valence shell electron pair repulsion theory
What is VSEPR
The electron pairs (both shared and unshared) in the outermost energy level try to get as far apart from each other as possible, this determines the shape of the molecule
Linear
2 or 3 atoms connected together in a straight line (180 degrees)
For 3 atoms, the central atom must have no unshared electron pairs
Example of linear
H2
CO2
Bent
3 atoms
The central atom has 1 or 2 unshared electron pairs and thus are more repulsive to the other atoms
If there are 2 pairs then there is more repulsion
Causes bent shape (approximately 104.5 degrees)
Example of bent
H2O
Trigonal planar
4 atoms
Central atom has no unshared electrons
About 120 degrees
Example of rigonal planar
CH2O
Pyramid
4 atoms - but the central atom has an unshared pair
About 107 degrees
Pyramid example
NH3
Tetrahedral
5 atoms
Central atom has no unshared pairs and has 8 valence electrons
About 109.5 degrees
Example of tetrahedral
CH4
Trigonal Bipyramidal
6 atoms
No unshared pairs
About 120 degrees
Example of trigonal bipyramidal
PF5
When can a central atom have an extended octet
Elements in period 3 or higher when bonded with Cl or F
Polar bonds
Bonds where the electrons are shared unequally between atoms
An atom that is more electronegative will… (for polarity)
Pull on the electrons
When atoms are different…. (for polarity)
Each has a different pull on the electrons
So, a bond of the same elements will always be covalent and non-polar because have the same electronegativity
How to do polarity
The atom that is more electronegative will be the one where the electrons spend most of their time (make a half eight sign thing with a minus for most electronegative one)
Non-polar bonds
Electrons are shared equallty between 2 atoms
Atoms that are the same…
Have the same electronegativity and thus are the same and are not polar
What about a central atom surrounded by atoms that are all the same?
It is non-polar except for when there is an unshared pair of electrons on the central atom or there is a double bond on only one of the bonds
What about different atoms around a central atom?
Will be polar
A _____ covalent bond consists of 2 shared electrons
Single
Ionic bonding
Gaining/losing electrons
Metal and nonmetal
Covalent bonding
Sharing electrons
Two nonmetals
Ionic compounds are made up of ______, which are very large structures consisting of alternating + and - ions
Crystals
When nitrogen bonds covalently it will make ____ bonds
3 (because 5 valence electrons)
Ionic compounds will conduct an electric current in the _____ state
Solid
Metals are ______, which means they can be hammered into different shapes
Malleable
What is the only element in group 1 to bond covalently?
Hydrogen
A double covalent bond has ____ shared electrons
4
In a ____ covalent bond, electrons are shared unequally
Polar
