AS physical

Question 1

What is the formula for the number of electrons in each shell

Answer 1

2n^2 where n is the number of the shell

Question 2

Explain the process of TOF Mass spectrometry (6 steps)

Answer 2

System is put into a vacuum to avoid collisions with air
Sample is ionised by dissolving in volatile solvent and passing through high voltage needle
Positive ions accelerated to negative plate according to their size and charge
Ions form a beam and travel through flight tube
Ions detected as positive ions pick up electrons and cause current to flow
Data is sent to a computer to be analysed

Question 3

What is m/z ratio equivalent to for singly charged ion

Answer 3

mass number

Question 4

Give two uses of mass spectrometry

Answer 4

identifying substances on crime scene (eg. drugs)
identifying elements on different planets

Question 5

What do the SPDF shapes represent

Answer 5

volume of space where there is a 95% chance of finding an electron

Question 6

state the order of electron orbitals up until 5p

Answer 6

1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p

Question 7

explain the trend in ionisation energy across a period

Answer 7

increases due to increasing nuclear charge with no added shielding. For group 3 and 6, it can decrease as the new electron operates in a higher sub-orbital, so less energy is required to remove it.

Question 8

Define the avagadro constant

Answer 8

the number of atoms in 12g of carbon 12

Question 9

units for volume in PV=nRT

Answer 9

m^3

Question 10

define empirical formula

Answer 10

the formula that represents the simplest whole number ratio of the atoms of each element present in a compound

Question 11

Define molecular formula

Answer 11

the actual number of atoms of each element in one molecule of a compound

Question 12

what is atom economy

Answer 12

mass of desired product/ mass of reactants

Question 13

name 3 properties of ionic compounds

Answer 13

high melting temperatures
conduct electricity in molten/ aqueous state
brittle

Question 14

explain why ionic lattices are brittle

Answer 14

a shift in the plane of atoms causes ions of the same charge to contact. These then repel, causing the compound to shatter

Question 15

give two properties of molecular structures

Answer 15

low melting/ boiling points
poor conductors of electricity

Question 16

Explain coordinate bonding

Answer 16

An atom with a lone pair donates the lone pair to an electron-deficient atom. Ie. All of the electrons in the shared pair come from one atom

Question 17

Give 4 properties of metals

Answer 17

conductors of electricity and heat
strong
malleable and ductile
high melting points

Question 18

What two things determine the strength of a metal

Answer 18

charge of ion
size of ion

Question 19

Define electronegativity

Answer 19

the power of an atom to attract the electron density in a covalent bond towards itself

Question 20

Define polarity

Answer 20

the unequal sharing of the electrons between atoms that are bonded together covalently

Question 21

Give two pieces of evidence for van de Waals forces

Answer 21

boiling points of noble gases increase down the group
boiling points of hydrocarbons increase with increasing chain length

Question 22

Give the piece of evidence for hydrogen bonding

Answer 22

higher boiling points for hydrides of the NOF elements

Question 23

Explain why ice is less dense than water

Answer 23

the hydrogen bonds no longer break, so keep the water molecules a fixed distance apart. To fit this structure, the molecules are further apart

Question 24

bond angle and shape of a molecule with four electron pairs (eg. CH4)

Answer 24

tetrahedron, 109.5

Question 25

bond angle and shape of a molecule with 5 electron pairs

Answer 25

trigonal bypyramidal, 120 and 90

Question 26

bond angle and shape of a molecule with 6 electron pairs

Answer 26

octahedral, 90

Question 27

bond angle and shape of a molecules with 3 bonding pairs and 1 lone pair

Answer 27

triangular pryamid, 107

Question 28

bond angle and shape of a molecule with 2 bonding pairs and 2 lone pairs

Answer 28

v-shape, 104.5

Question 29

bond angle and shape of a molecule with 4 bonding pairs and 2 lone pairs

Answer 29

square planar, 90

Question 30

Describe the structure of diamonds

Answer 30

each carbon covalently bonded to four other carbon atoms, in giant 3d structure

Question 31

describe the structure of graphite

Answer 31

each carbon atom covalently bonded to three other carbon atoms in 2d structure. These 2d layers are connected by van de Waals forces

Question 32

Explain the structure of buckminsterfullerene

Answer 32

60 carbon atoms, each bonded to three other carbon atoms, and arranged in a football-like shape

Question 33

give four uses of thermochemistry

Answer 33

measure energy values used for fuels calculate energy for different industrial processes theoretical energy to break bonds, energy released when bonds are made predicts the feasibility of a reaction

Question 34

give three ways in which a flame calorimeter is made more efficient

Answer 34

spiral chimney made of copper flame is enclosed fuel burns in pure oxygen

Question 35

Give 5 things that affect rate of reaction

Answer 35

temperature concentration pressure surface area catalysts

Question 36

what is the name of the state of the intermediate species at the top of an enthalpy diagram

Answer 36

transition state

Question 37

How does a catalyst affect rate of reaction

Answer 37

provides an alternative energy pathway with a lower activation energy

Question 38

What do catalytic converters do

Answer 38

reduce the amounts of polluting gases by catalysing reactions that remove nitrogen oxides, unburned hydrocarbons and carbon monoxides

Question 39

define adsorption

Answer 39

reactants forming weak bonds with the catalyst surface

Question 40

define desorption

Answer 40

products breaking away from the surface of a catalyst

Question 41

Define dynamic equilibrium

Answer 41

a situation in which the composition of a constant concentration reaction mixture does not change because the forward reaction and backward reaction happen at the same rate

Question 42

state the condition for equilibrium to be reached

Answer 42

closed system

Question 43

Explain how we know when an equilibrium has been reached

Answer 43

macroscopic properties are constant eg. density, concentration, colour, pressure

Question 44

State Le Chatelier's principle

Answer 44

If a system at equilibrium is disturbed, the equilibrium moves in the direction that tends to reduce the disturbance.

Question 45

What do catalysts affect concerning equilibrium

Answer 45

the rate at which an equilibrium is reached

Question 46

What is the catalyst for the haber process

Answer 46

iron

Question 47

four reasons that a low temperature, high pressure and excess steam cannot be met in an industrial situation for the production of ethanol from hydration of ethene

Answer 47

high pressure causes polymerisation building and maintenance costs for high pressure systems low temperature affects rate of reaction steam dilutes the catalyst

Question 48

What catalyst is used for production of ethanol from hydration of ethene

Answer 48

phosphoric acid

Question 49

give the equation for the Kc expression

Answer 49

Kc=[products]/ [reactants]

Question 50

What affects the Kc expression

Answer 50

temperature

Question 51

If Kc > 1 where is equilibrium

Answer 51

to the right

Question 52

For an exothermic reaction, what is the effect of increasing temperature on Kc

Answer 52

Kc

Question 53

define reducing agent

Answer 53

electron donor

Question 54

define oxidation states

Answer 54

the number of electrons lost or gained by an atom in a compound compared to the uncombined atom.

Question 55

Oxidation state of hydrogen

Answer 55

+1 except metal hydrides where it is -1

Question 56

Oxidation states of group 1, group 2 and Alumininium respectively

Answer 56

always +1,+2,+3

Question 57

oxidation state of Oxygen

Answer 57

-2 except peroxides (-1) and OF2 (+2)

Question 58

oxidation state of fluorine

Answer 58

always -1

Question 59

oxidation state of chlorine

Answer 59

-1 except compounds with Fluorine or Oxygen where it has positive values

Question 60

What is the rule for which atoms have negative oxidation numbers

Answer 60

the most electronegative atom has a negative oxidation state