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Shapes of molecules and IMFs - Coggle Diagram
Shapes of molecules and IMFs
Electron-pair repulsion theory
The electron pairs surrounding a central atom determine the shape of a molecule
e- pairs repel one another so they are arranged as far apart as possible
A lone pair of electrons are slightly closer to the central atom so occupy more space therefore repelling more strongly than a bonding pair
Molecular Shapes
Linear
2 bonded pairs, 0 lone pairs
180° bond angle
Trigonal Planar
3 Bonded pairs, 0 lone pairs
120° bond angle
Non-linear
2 bonded pairs, 2 lone pairs
104.5° bond angle
Octahedral
5 bonded pairs, 0 lone pairs
90° bond angle
Pyramidal
3 bonded pairs, 1 lone pair
107° bond angle
Tetrahedral
109.5° bond angle
4 bonded pairs, 0 lone pairs
Electronegativity
The attraction of a bonded atom for the shared pair of electrons in a covalent bond
Across the periodic table
atomic radius decreases
Nuclear charge increases
The more up and across (right) the periodic table the higher the electronegativity
polar and non polar molecules
polar
Bonded atoms are different
Bonded atoms have a difference in electronegativity
Bonded electron pair is shared unequally
polar molecules
component bonds have permanent polar dipoles
Dipoles act in different directions but do not exactly oppose one another
Non polar
bonded atoms have the same or similar electronegativity
Bonded atoms are the same