module two: chapter six: shapes of molecules + intermolecular forces

Question 1

electron repulsion theory?

Answer 1

electrons repel each other, so arrangement of electron pairs minimises repulsion so holds bonded atoms in definite shape

Question 2

what types of bonded pairs repel strongest?

Answer 2

bonded pair+ bonded pair< bonded pair+ lone pair< lone pair+ lone pair

Question 3

what is the shape name with 4 bonded pairs?

Answer 3

tetrahedral

Question 4

what is the bond angle of tetrahedral?

Answer 4

109.5

Question 5

what is the shape name with 3 bonded pairs and 1 lone pair?

Answer 5

pyramidal

Question 6

what is the bond angle of pyramidal?

Answer 6

107

Question 7

what is the shape name with 2 bonded pairs and 2 lone pairs?

Answer 7

non linear

Question 8

what is the bond angle of non linear?

Answer 8

104.5

Question 9

what is the shape name with 2 electron pairs?

Answer 9

linear

Question 10

what is the bond angle of linear?

Answer 10

180

Question 11

what is the shape name with 3 electron pairs?

Answer 11

trigonal planar

Question 12

what is the bond angle of trigonal planar?

Answer 12

120

Question 13

what is the shape name with 6 electron pairs?

Answer 13

octahedral

Question 14

what is the bond angle of octahedral?

Answer 14

90

Question 15

electronegativity?

Answer 15

attraction of a bonded atom for the pair of electrons in a covalent bond

Question 16

how is electronegativity measured?

Answer 16

pauling scale, it increases up and across the periodic table, F being the most.

Question 16

what happens if the electronegativity difference is large?

Answer 16

one bonded atom will have a much greater attraction for the shared pair than the other bonded atom. the more electronegative atom will now be ionic rather than covalent.

Question 16

what does a large pauling value represent?

Answer 16

the atoms of the element are very electronegative

Question 17

when is a bond non polar?

Answer 17

bonded electron pair is shared equally, bonded atoms are same or have similar electronegativity

Question 18

when is a bond polar?

Answer 18

bonded electron pair is shared unequally, bonded atoms are different or have different electronegativity

Question 19

what are the polar properties of H2O?

Answer 19

2 O-H bonds have permanent dipole, 2 dipoles act different directions- do not oppose each other

Question 20

what are the polar properties of CO2?

Answer 20

2 C//O bonds permanent dipoles, 2 dipoles act opposite directions- oppose one another. over whole molecule, the dipoles cancel out and is 0

Question 21

intermolecular forces?

Answer 21

weak interactions betweem dipoles of different molecules: induced dipole dipole, permanent dipole dipole, h bonding

Question 22

bond enthalpy of london forces?

Answer 22

1-10

Question 23

bond enthalpy permanent dipole?

Answer 23

3-25

Question 24

bond enthalpy h bonds?

Answer 24

10- 40

Question 25

london forces?

Answer 25

intermolecular forces that exist between all molecules (polar + non polar). act between induced dipoles of different molecules

Question 26

strength of london forces?

Answer 26

the more electrons the stronger the forces

Question 27

permanent dipole-dipole interactions?

Answer 27

act between permanent dipoles in different polar molecules

Question 28

simple molecular substance?

Answer 28

made up of simple molecules, forms simple molecular lattice when solid

Question 29

simple molecular lattice?

Answer 29

molecules held by weak intermolecular forces, atoms within molecules bonded together by strong covalent bonds

Question 30

melting and boiling points of s.m.l?

Answer 30

intermolecular forces broken by low temps, low boiling points, only intermolecular breaks not covalent

Question 31

what happens when simple molecular compound added to non polar solvent?

Answer 31

intermolecular forces from between molecules and solvent, the interactions weaken forces so they break and compound dissolves - soluble

Question 32

what happens when s.m.c added to polar solvent?

Answer 32

little interactions between molecules and solvent, intermolecular bonding in solvent too strong to be broken- insoluble

Question 33

electrical conductivity of s.m.l?

Answer 33

no

Question 34

h bonds?

Answer 34

permanent dipole- dipole between molecules with electronegative atom with lone pair, or a H atom attached to an electronegative atom

Question 35

how strong are H bonds?

Answer 35

strongest intermolecular force

Question 36

properties of water?

Answer 36

ice less dense than water- H bonds hold water molecules apart in open lattice, in ice the molecules are further away so floats above water. high boiling pts