Shapes of Molecules
- Wedge = Coming out
- Dashed line = Going behind
- Trigonal bipyramidal angles = 120 and 90 1 dash 1 wedge 3 normal
- Wedge and dashed at 120
- Octrahedral 2 dashed 2 wedged 2 normal 90 degrees
- Van der waals = Both Permenant and induced dipole forces so must define which your talking about when you use it.
- Instaneous Induced Dipole forces = London Forces=Dispersion Forces
- H bonding only happens with H and small+electronegative atom
- Strongest: F>O>N>C :Weakest
- H bond is 180 degrees
- Ice Less dense then water as in ice rings of 6 H2O molecules which H bond and the distance is larger than when the ice melts into water as the ring structure is destroyed
- DNA = Double helix each strand is held to together by H bonds
- Adenine Thymine 2 H bonds Guanine and Cytosine 3 H Bonds
- Sublimation = when a solid turns straight into a gas without melting
Ability to reduce another molecule depends on high easily the molecule itself can lose electrons eg iodine is a strong reducing agent whereas fluorine isn't.
On the other hand Oxidising ability depends on how easily it can be reduced itself so fluorine is a strong oxidising agent as it can easily gain elctrons due to high electronegativity.
- Solute particles must be seperated from each other and must be surronded by solvent particles
- Solvent-Solute forces must be stronger than Solvent-Solvent and Solute-Solute
- Like disolves like, so a polar substance disolves in another polar substance
- If mixture of both polar and non polar areas eg an alcohol solute must contain both polar and non polar bonds.
- Group 2 hydorxides solubility increases down group Berylium doesnt disolve.
- Sulfates decrease down group Barium sulfate is insoluable.