Physical Chemistry Year 1

Question 1

what is empirical formula

Answer 1

The simplest form

Question 2

what is molecular formula

Answer 2

the natural formula

Question 3

general formula of methane

Answer 3

CnH2n+2

Question 4

general formula of methene

Answer 4

CnH2n

Question 5

what is structural formula

Answer 5

the structural arrangement

Question 6

what is displayed formula

Answer 6

shows every bond

Question 7

what is skeletal formula

Answer 7

shows only bonds and anything that is not carbon

Question 8

define homologous series

Answer 8

all the members:
- follow a general formula
- react in a very similar way
- differ from the next by a carbon
- do not have same physical properties due to the size of the chain

Question 9

define functional group

Answer 9

group of atoms responsible for how a compound reacts

Question 10

what is a position isomer

Answer 10

where the functional group is in a different position

Question 11

what is a chain/ structural isomer

Answer 11

when there is a different structural arrangement of atoms

Question 12

what is a functional group isomer

Answer 12

where there is a different arrangement of the same molecular formula, so the functional group is different

Question 13

what is a stereoisomer

Answer 13

where there is a different spacial arrangement, but same structural formula

Question 14

how do you draw a stereoisomer

Answer 14

Must be a double bond
the atom with the higher atomic number takes priority
E isomer:
- 1 is on the top row, one is on the bottom
- they should be diagonally opposite
Z isomer:
- both should be on the top or bottom row

Question 15

what is an E stereoisomer

Answer 15

where the priority atoms are apart

Question 16

what is a Z stereoisomer

Answer 16

where the priority atoms are together

Question 17

define electronegativity

Answer 17

power of an atom to attract negative charge towards itself

Question 18

during electronegativity there will be a significant impact…

Answer 18

…on the behaviour of covalent molecules, because it affects the polarity

Question 19

the bigger the difference of electronegativity…

Answer 19

…the more polar the bonds are

Question 20

what is in a polar bond

Answer 20

where there is an unequal share of electrons

Question 21

why does the largest bond angle exist between electron pairs

Answer 21

electron pairs naturally repel each other

Question 22

how do you work out the bond angle when lone pairs are present

Answer 22

for every lone pair, reduce the bond angle by 2.5 degrees

Question 23

what is the bond angle for a linear molecule

Answer 23

180 degrees

Question 24

what is the bond angle for a v- shaped molecule

Answer 24

104.5 degrees

Question 25

what is the bond angle for a trigonal planar molecule

Answer 25

120 degrees

Question 26

what is the bond angle for a triangular pyramid molecule

Answer 26

107 degrees

Question 27

what is the bond angle for a tetrahedral molecule

Answer 27

109.5 degrees

Question 28

what is the bond angle for a trigonal bipyramid molecule

Answer 28

90 degrees, and 120 degrees

Question 29

what is the bond angle for an octahedral molecule

Answer 29

90 degrees

Question 30

define dipole

Answer 30

difference in electronegativity

Question 31

what are the most electronegative atoms

Answer 31

-fluorine
-oxygen
-chlorine
-nitrogen

Question 32

what are the 3 types of intermolecular forces in order of strongest to weakest

Answer 32

1. hydrogen bonding
2. permanent dipole to dipole attraction
3. van der waals forces

Question 33

what happens in the hydrogen bond IMF

Answer 33

-H bonds to N, O, F
-lone pairs in each bond to a hydrogen atom

Question 34

what happens in the permanent dipole to dipole attraction IMF

Answer 34

-dipole is permanent due to atoms always having a difference in electronegativity
-they have a lattice- like structure

Question 35

what happens in the van der waals forces IMF

Answer 35

uneven distribution of electrons cause a temporary dipole in one molecule, so it induces it in another and causes an electromagnetic force of attraction