chem chapter 6

Question 1

what is electron repulsion theory

Answer 1

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

Question 2

how much do lone pairs reduce bond angle by

Answer 2

2.5 degrees

Question 3

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

Answer 3

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

Question 4

what is electronegativity
what is a dipole

Answer 4

the ability of a bonded atom to attract electrons in a covalent bond
- separation of charges

Question 5

Bond type
covalent
polar covalent
ionic

whats their EN difference

Answer 5

covalent - 0
PC- 0-1.8
Ionic- 1.8<

Question 6

intermolecular forces-
give three types
Bond enthalphy

Answer 6

weak interactions between dipoles of different molecules
-london forces, permanent dipole-dipole interactions,h bonding
how much energy needed to break IM forces

Question 7

what are London forces and how do they occur

Answer 7

• 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

Question 8

how do more electrons impact London forces?

Answer 8

• 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

Question 9

why does p dipole-dipole interactions require more energy to break

Answer 9

you need to overcome London forces and P d-d Interactions

Question 10

why are polar substance unable to dissolve in non polar substances

Answer 10

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

Question 11

Define hydrogen bonding

Answer 11

type of permeant dipole-dipole interaction involving an electronegative atom with a lone pair of electrons and a hydrogen atom attached to the atom

Question 12

why is soild ice less dense in water

Answer 12

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