chem chapter 6 Flashcards
what is electron repulsion theory
electron pairs repel each other
electron pairs are far way from each other as possible so are arranged as far as possible
arrangement of electron pairs minimises repulsion as far as possible and holds bonded atom in a definite shape
how much do lone pairs reduce bond angle by
2.5 degrees
number of bonding pairs+ lone pairs
2 + 0
3 +0
2+1
4+0
3+1
2+2
5+0
4+1
3+2
6+0
5+1
4+2
shape
1) linear
trigonal planar
bent v shape
tetrahedral
trigonal pyramidal
bent v shape
trigonal bipyramidal
trigonal pyramidal
trigonal planar
octahedral
square pyramid
square planar
what is electronegativity
what is a dipole
the ability of a bonded atom to attract electrons in a covalent bond
- separation of charges
Bond type
covalent
polar covalent
ionic
whats their EN difference
covalent - 0
PC- 0-1.8
Ionic- 1.8<
intermolecular forces-
give three types
Bond enthalphy
weak interactions between dipoles of different molecules
-london forces, permanent dipole-dipole interactions,h bonding
how much energy needed to break IM forces
what are London forces and how do they occur
- weak if forces that exist between all molecules regardless of polarity, electrons are constantly moving, so can gather at one point in the atom causing an instaneous dipole, which induces instaneous dipoles in neighbouring molecules , these all together form a dipole
how do more electrons impact London forces?
- more electrons will mean a larger instaneous dipole forming as more electrons gathering at the same place so there will be larger induced reactions as the attractive forces between molecules are stronger so more energy needed to break these IM forces
why does p dipole-dipole interactions require more energy to break
you need to overcome London forces and P d-d Interactions
why are polar substance unable to dissolve in non polar substances
as the iM forces between both don’t attract each other and the intermolecular bonding between polar molecules are too strong to be broken down so they don’t dissolve
Define hydrogen bonding
type of permeant dipole-dipole interaction involving an electronegative atom with a lone pair of electrons and a hydrogen atom attached to the atom
why is soild ice less dense in water
as hydrogen bonds hold water molecules further apart when frozen and solid in an open lattice structure
the two lone pairs and two hydrogen atoms hold water molecules apart at 180 degrees