Chemistry Revision
Organics
Structure and Bonding
Chemical Reactivity
Lewis Structures
Count number of VALENCE electrons
Atom furthest from a full VALENCE shell is central
Molecular shapes
Regions of electron density repel for max separation, therefore depending on the number of regions will depend on the overall shape of the molecule.
Tetrahedral 4/4 Regions bonded. Bond agles of 109 deg.
Trigonal Planar 3/3 regions bonded. Bond angles of 120 deg.
Trigonal Pyramidal 3/4 regions bonded. Bond angles of 109 deg.
Bent 2/4 regions bonded. Bond angles of 109 deg
Bent 2/3 regions bonded. Bond angles of 120 deg.
Linear 2/2 regions bonded. Bond angles of 180 deg.
EXPLAINING SHAPE PARAGRAPH
Draw Lews Diagram
NUmber of electron density regions around central atom
State groups of electron density repel each other for maximum speration
State base shape of molecule and bond angles between bonds
State number of groups bonding and non-bonding and the overall shape
Polarity
Eectronegativity - is a value that represents the strength that an atom attracts a bonding pair of electrons
F>O>N>Cl are all electronegative atoms going from most to least electronegative (FONCl)
A bond will be polar when their is a difference between the electronegativity. This creates a bond dipole
Crystalline Solids
Molecular solids are one of four types
Molecular solids - Made up of non-metal molecules
Metallic Solids - Made up of only metallic atoms
Covalent Network Solids - Made up of only non-metal atoms
Ionic Solids - Made up of metal and non-metal atoms
Properties of Cyrstalline Solids
Hardness - A measure of how much force is needed to break bonds in a solid
Malleability - The abolity of a solid to change its shape without fracturing when force is applied
Boiling Point - The temperature at which a substane changes from liquid to gas
Melting Point - The temperature at which a substance changes from a solid to a liquid
Ductility - The ability of a solid to be stretched into a wire when force is applied
Solubility - The abolity of a solid to dissolve in a liquid; A solid will dissolve in a liquid when the bonds formed between the particles in a liquid are equal or stronger than the bonds between particles in the solid