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A Level Chemistry - Physical Chemistry > 3.1.1 Atomic Structure > Flashcards

3.1.1 Atomic Structure Flashcards

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1
Q

Definition of an isotope

A

Same number of protons different number of neutrons

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2
Q

Relative mass of an electron

A

1/1836

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3
Q

Is the mass number the top or bottom number

A

Top

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4
Q

Is the atomic number the top or bottom number

A

Bottom

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5
Q

What is the mass number

A

Number of protons and neutrons

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6
Q

What is the atomic number

A

The number of protons
& Electron if the element is neutral

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7
Q

What holds an atom together

A

Electrostatic attraction between the positive nucleus and the negatively charged electrons orbiting around it

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8
Q

How is an ions formed

A

When atoms gain or lose electrons

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9
Q

Chemical properties of isotopes + why

A

Isotopes of the same element have the SAME CHEMICAL CHARACTERISTICS because the have the same number of electrons on OUTER SHELL.
( electrons take part in chemical reactions and therefore determine the chemistry of an atom)

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10
Q

Isotopes physical properties + why
(Compared to the same element)

A

Different mass and density
Different number of neutrons

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11
Q

How to calculate relative atomic mass from a mass spectra

A

(Relative abundance x mass)+(relative abundance x mass) etc / total abundance aka percentage (usually adds to 100 but check)

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12
Q

The abundance tells us….

A

How common each isotope is

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13
Q

What do you use a mass spectrometer for

A

Determining mass number and abundance of isotopes

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14
Q

What is in the sample chamber in a mass spectrometer

A

All the different isotopes of that element

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15
Q

Samples need to be…. before it enters the mass spectrometer

A

Ionised

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16
Q

What are two ways to ionise a sample

A

Electron spray ionisation
Electron impact ionisation

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17
Q

How does electrons spray ionisation work

A

Sample dissolved in a volatile solvent
Injectedthrough small nozzle at high pressure and voltage
Each Particles gain H+ ion

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18
Q

How does electron impact ionisation work

A

Sample is vaporised
Electron gun fires high energy electrons at it
Electron knocked off forming +1 ion

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19
Q

Definite relative atomic mass

A

The average mass of one atom of an element compared with 1/12 of the mass of an atom of carbon-12

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20
Q

Why is TOF kept in a vacuum

A

To prevent ions from colliding with air molecules

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21
Q

Through which form of ionisation is fragmentation most likely to occur

A

Electron impact ionisation

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22
Q

Ions are all accelerated to have the same ….

A

Kinetic energy

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23
Q

Equation for kinetic energy

A

KE= 1/2 x m x v^2

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24
Q

Definition first ionisation energy

A

The energy needed to remove one mole of electrons from one mole of atoms in their gaseous state to form one mole of 1+ ions

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25
Q

Define second ionisation energy

A

The energy needed to remove one mole of electrons from one mole of 1+ ions in their gaseous state to form one mole of 2+ ions.

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26
Q

What did John dalton do x2

A

Atoms were solid spheres
Difference spheres made different elements (:

27
Q

What did JJ Thompson do

A
  • plum pudding model
  • discovered electrons
28
Q

What is Rutherford do + model

A

Alpha scattering experiment
Nuclear model + discovered nucleus

29
Q

What did Bohr do x3

A

Electrons in fixed orbits
Each shell fixed energy
When electrons move between shells electromagnetic radiation is emitted or absorbed

30
Q

Definition of relative atomic mass

A

Average mass of one atom of an element compared with 1/12 of the mass of an atom of carbon-12

31
Q

Explain how ions are accelerated, detected and have their abundance determined
in a time of flight (TOF) mass spectrometer

A

Attraction to negatively charged plate
Ions detected by gaining electrons
Abundance determined by current flowing in the detector

32
Q

2 difference between model used now and plum pudding model

A

Nucleus contains protons AND neutrons
Electrons are arranged in energy levels

33
Q

Ionisation energy equations
1st
2nd
3rd

A

E(g) —> E+(g) + E-
E(g)+ —> E2+(g) + E-
E2+ (g) —-> E3+(g) + E-

34
Q

Abundance is …… to the size of the current

A

Proportional

35
Q

How to calculate the mass of an ion in kg

A

Atomic number x 10^-3 / 6.022x10^23

36
Q

Which shell empties first 4s or 3d

A

4S
PLEASE REMBER

37
Q

Why does aluminium not fit ionisation trend

A

Electron in 3p orbital higher in energy level than 3s orbital in magnesium

38
Q

Why does sulphur not fit the trend of ionisation

A

Outer electron in 3p sub shell begin to pair
So they repel

39
Q

What is the little line in a mass spectrometer due to

A

Presence of 2H or 13C

40
Q

How to find the relative molecular mass from a mass spectrometer

A

Where the peak is
Greatest m/z ratio

41
Q

Which is the one where you take off one for the relative molecular mass

A

Electron spray ionisation
They gain a H+

42
Q

Which two element are the exception to the electron configuration

A

Cr and Cu

43
Q

Electron configuration of cr

A

1s2 2s2 2p6 3s2 3p6 3d5 4s1

44
Q

Electron configuration of cu

A

1s2 2s2 2p6 3s2 3p6 3d10 4s1

45
Q

In a mass spectrometer the ions travel at a ….

A

Constant speed

46
Q

Relative molecular mass

A

The average mass of a molecule when measured on a scale on which the mass of an atom of carbon 12 is exactly 12

47
Q

Relative isotopic mass

A

The mass of an atom of an isotope of an element when measured in a scale on which the mass of an atom of carbon 12 is exactly 12

48
Q

What does the last peak on a mass spectra for molecules indicates

A

It is the molecular ion peak
It is the same as the relative molecular mass of the molecule

49
Q

What’s key to remember about the electron configuration order

A

4s comes before 3d
It empties and fills first

50
Q

Ionisations energy always have a positive/negative charge + why

A

Positive
Endothermic as the process requires energy

51
Q

What 3 things effect the ionisation energy

A

Shielding
Nuclear charge
Atomic size

52
Q

Why is ionisation necessary in time of flight x2

A
  • they can be accelerated by magnetic field
  • ions create a current when hitting the detector
53
Q

Isotopes have the same/different chemical properties

A

Same

54
Q

Ionisation energy increase/decreases across period 2 or 3 +why

A

Increases because number of protons increasing but SHIELDING is the similar.
Stronger attraction between outer most electron and nucleus

55
Q

As you move down group 2 the first ionisation energies

A

Decreases.

56
Q

Which ionisation means the m/z ratio is one higher than the relative mass + what do you do

A

Electron spray ionisation means the m/z ration is +1 than it should be because it gained H+
Take away 1 then do

57
Q

Acceleration in TOF is done by…

A

ELECTRIC field

58
Q

Why does radius decrease/increase across period 2

A

Decrease
Increase nuclear traction as the number of protons increase with the same shielding. So the electrons in outer shell are more strongly attracted in.

59
Q

The ion that reaches the detector forts in TOF would have the highest/lowest m/z ratio

A

Lowest

60
Q

2 difference between Rutherford model and current model

A

current
neutrons AND PROTONS
ELECTRONS IN DIFFERENT ENERGY LEVELS

61
Q

In terms of ionisation energy do all the periods follow the same trend

A

Yes

62
Q

Although not on spec can ask about trend in ionisation energies across period 2. What do you say…?

A

The exact same pattern as for period 3 with the same reasons. Just don’t say 3p orbitals etc because it’s two. If in doubt don’t say which letter.

63
Q

Which has a greater first ionisation energy H or He

A

Helium
The electron is begin removed from the same orbital as hydrogen but there are more protons 2 instead of 1 so the is a grate attraction
+ ionisation energy increases top right of periodic table

64
Q

Technique for doing electron configuration of ions

A

Do original elements first then ion
DO THIS

A Level Chemistry - Physical Chemistry (8 decks)

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