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A-level Chemistry > AS physical > Flashcards

AS physical Flashcards

Atomic structure, amount of substance, bonding, energetics, kinetics, equilibria, redox

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1
Q

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

A

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

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2
Q

Explain the process of TOF Mass spectrometry (6 steps)

A

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

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3
Q

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

A

mass number

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4
Q

Give two uses of mass spectrometry

A

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

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5
Q

What do the SPDF shapes represent

A

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

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6
Q

state the order of electron orbitals up until 5p

A

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

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7
Q

explain the trend in ionisation energy across a period

A

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.

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8
Q

Define the avagadro constant

A

the number of atoms in 12g of carbon 12

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9
Q

units for volume in PV=nRT

A

m^3

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10
Q

define empirical formula

A

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

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11
Q

Define molecular formula

A

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

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12
Q

what is atom economy

A

mass of desired product/ mass of reactants

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13
Q

name 3 properties of ionic compounds

A

high melting temperatures
conduct electricity in molten/ aqueous state
brittle

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14
Q

explain why ionic lattices are brittle

A

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

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15
Q

give two properties of molecular structures

A

low melting/ boiling points
poor conductors of electricity

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16
Q

Explain coordinate bonding

A

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

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17
Q

Give 4 properties of metals

A

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

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18
Q

What two things determine the strength of a metal

A

charge of ion
size of ion

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19
Q

Define electronegativity

A

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

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20
Q

Define polarity

A

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

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21
Q

Give two pieces of evidence for van de Waals forces

A

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

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22
Q

Give the piece of evidence for hydrogen bonding

A

higher boiling points for hydrides of the NOF elements

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23
Q

Explain why ice is less dense than water

A

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

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24
Q

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

A

tetrahedron, 109.5

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25
Q

bond angle and shape of a molecule with 5 electron pairs

A

trigonal bypyramidal, 120 and 90

26
Q

bond angle and shape of a molecule with 6 electron pairs

A

octahedral, 90

27
Q

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

A

triangular pryamid, 107

28
Q

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

A

v-shape, 104.5

29
Q

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

A

square planar, 90

30
Q

Describe the structure of diamonds

A

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

31
Q

describe the structure of graphite

A

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

32
Q

Explain the structure of buckminsterfullerene

A

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

33
Q

give four uses of thermochemistry

A

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

34
Q

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

A

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

35
Q

Give 5 things that affect rate of reaction

A

temperature
concentration
pressure
surface area
catalysts

36
Q

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

A

transition state

37
Q

How does a catalyst affect rate of reaction

A

provides an alternative energy pathway with a lower activation energy

38
Q

What do catalytic converters do

A

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

39
Q

define adsorption

A

reactants forming weak bonds with the catalyst surface

40
Q

define desorption

A

products breaking away from the surface of a catalyst

41
Q

Define dynamic equilibrium

A

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

42
Q

state the condition for equilibrium to be reached

A

closed system

43
Q

Explain how we know when an equilibrium has been reached

A

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

44
Q

State Le Chatelier’s principle

A

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

45
Q

What do catalysts affect concerning equilibrium

A

the rate at which an equilibrium is reached

46
Q

What is the catalyst for the haber process

A

iron

47
Q

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

A

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

48
Q

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

A

phosphoric acid

49
Q

give the equation for the Kc expression

A

Kc=[products]/ [reactants]

50
Q

What affects the Kc expression

A

temperature

51
Q

If Kc > 1 where is equilibrium

A

to the right

52
Q

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

A

Kc

53
Q

define reducing agent

A

electron donor

54
Q

define oxidation states

A

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

55
Q

Oxidation state of hydrogen

A

+1 except metal hydrides where it is -1

56
Q

Oxidation states of group 1, group 2 and Alumininium respectively

A

always +1,+2,+3

57
Q

oxidation state of Oxygen

A

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

58
Q

oxidation state of fluorine

A

always -1

59
Q

oxidation state of chlorine

A

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

60
Q

What is the rule for which atoms have negative oxidation numbers

A

the most electronegative atom has a negative oxidation state

A-level Chemistry (6 decks)

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