Atomic Structure Flashcards

1
Q

What does a Mass Spectrometer measure?

A

The relative mass of isotopes

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2
Q

What are the stages a Time of Flight mass spectrometer?

A

• ionisation
• acceleration
• ion drift (distance)
• detection
• analysis

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3
Q

Outline Electrospray Ionisation

A
  • sample dissolved in polar solvent
  • injected through a needle at a high voltage
  • each particle gains a proton (H+) to form 1+ ions
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4
Q

What is the equation for electrospray?

A

X(g) + H+ > XH+(g)

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5
Q

What is electron impact?

A

• high energy electrons fired from electron gun
• knocks of an electron from each particle
• form 1+ ion

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6
Q

What is the equation for Electron impact?

A

X(g) > X(g) + e-

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7
Q

What happenes during Acceleration in TOF?

A

• positive ions are accelerated by an electric field to a constant KE
( velocity depends in mass of ion)
Ions with lower mass travel faster

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8
Q

What happens during Ion Drift in TOF?

A

• ions separate
• they drift in a flight tube of know distance and time taken is recorded
• TOF depends on velocity

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9
Q

What happens during ion detection in TOF?

A

• positive ions hot detector and pick up an electron
• causes a current to flow
( more ions hitting detector bigger current)

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10
Q

Why is a vaccum required in TOF

A

So no other particles can be detected and interfere

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11
Q

Equation for mass(kg) of each 1+ particle

A

( Mass number/Avagadro ) / 1000

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12
Q

Equation to find Velocity with KE and mass

A

v = √2KE / m

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13
Q

What equation can you use if you’re not given distance?

A

m1 m2
—- = —-
(t1)2 (t2)2

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14
Q

What is the formula for relative atomic mass

A

average mass of an atom of an element
——————————————————-
1/12 mass if an atom an atom of 12C

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15
Q

Equation to calculate relative atomic mass from peaks

A

sum (m/z of a peak x abundance of that peak)
————————————————————
sum of abundances

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16
Q

what is fragmentation?

A

Bonds in covalent bonds break into fragments during electron impact ionisation

17
Q

What happens during fragmentation

A

bonds will gain a postitive charge
these give a peak

18
Q

What fragmentation happens in Electrospray

A

little fragmentation occurs so there are less peaks

19
Q

What is the Mr in Electrospray ionisation

A

the highest peak value minus one

20
Q

What is the Mr in Electron impact?

A

The peak with the highest m/z value

21
Q

What are shells matching sub-levels??

A

1 = s
2 = p
3 = d
4 = f

22
Q

What is the order of increasing energy levels?

A

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s….etc

23
Q

What are the maximum number of electrons in each sublevel

A

s = 2
p = 6
d = 10
f = 14

24
Q

Why does 4s fill before 3d

A

4d is lower in energy

25
Q

Why does Cr and Cu differ in electron configuration?

A

instead of 4s2 they have 4s1
they show a full/half subshell
they have lowere energies and represent more stable arrangements

26
Q

What is first ionisation energy?

A

The minimum amount of energy required to remove an electron from a gaseous atom

27
Q

What is the trend of Ionisation energy down a group and why?

A

• decreases
• bc it’s removed from a HIGHER principle energy level
• electron further from
• more sheilding
• less energy required to remove electron

28
Q

What is the trend of Ionisation energy across a group and why?

A

• increases
• protons increase
• constant sheilding
• more energy needed to remove electrons

29
Q

What is the mass of a proton

A

1

30
Q

What is the mass of a neutron?

A

1

31
Q

what is the mass of an electron

A

1/1800

32
Q

what is an isotope

A

atoms of an element with the same number of protons but different number of neutrons

33
Q

what is the definition of mass numbers

A

total number of protons and neutrons

34
Q

define atomic number

A

number of protons in an atom

35
Q

define atomic number

A

number of protons in an atom