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atomic structure Flashcards

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1
Q

what is the tof spectrometer

A

Detects the mass and relative abundance of isotopes

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2
Q

what are the 3 steps of using a tof mass spectrometer

A

ionisation, acceleration, detection

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3
Q

two types of ionisation

A

Electron impact:

Sample vapourised X(g)

Bombarded with electrons from electron gun

X(g)+ e- => X+(g)+ 2e-

Electro spray

Sample dissolved in a volatile solvent

Turned into a fine spay via a charged needle (increases the m/z value by 1)

H+ gained from a solvent

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

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4
Q

what happens during acceleration

A

Charged plates create an electric field

All ions accelerated forwards with the same kinetic energy (ion drift)

Have diff types velocities due to differences in mass

(More mass=less velocity)

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5
Q

what happens during detection

A

Negatively charged detector

Positive ions gain electrons at the plate, which cause an electric current

The current is monitored to give a spectra

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6
Q

what is a mass spectra

A

a graph that shows the relative abundances of the different isotopes (and their masses)

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7
Q

what is symbol for isotopic mass

A

m/z

(mass: charge ratio)

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8
Q

how to calculate isoptopic mass

A

find Ar

sum of isotopic mass*percentage

all divideby 100

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9
Q

how to calculate unknown isotopic mass

A
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10
Q

what else may show up in a mass spectrum?

A

very small peaks at Mr+1 made up of elemental molecules

i.e 13C and 2H

(only organic molecules)

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11
Q

how to find ratios of different isotopes forming

A
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12
Q

velocity calculations

(3 formulae need to be used)

A

KE= 1/2mv2 (rearrange to find v)

convert the grams of the mass of the ion to kg

d=tv (finds length of flight tube)

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13
Q

what are electron orbitals

A

where electrons are found, within energy levels

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14
Q

order of orbitals (low to high)

A

s, p, d, f

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15
Q

how many electrons does an orbital hold

A

2

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16
Q

what is s orbital

A

spherical in shape, holds up to 2

17
Q

what is p orbital

A

figure 8 shape

found in groups of 3 orbitals

18
Q

what is d orbital

A

various shapes

found in groups of 5 orbitals

∴ holds up to 10 electrons

19
Q

what orbitals are in each energy level

A

Energy level 1: 1s2

Total e:2

Energy level 2: 2s2,2p6

Total e:8

Energy level 3: 3s2,3p6,3d10

Total e:18

Energy level 4: 4s2,4p6,4d10,4f14

Total e: 32

20
Q

what is hund’s rule

A

electrons occupy empty orbitals b4 pairing b/c minimises repulsion

∴

21
Q

what does it means to be isoelectric

A

means that ions has the same configurstion as some noble gas

22
Q

exception to orbital energy levels

A

found in transition metals where 4s is filled in before 3d and electrons lost from 4s before 3d

23
Q

what is first molar ionisation energy

A

(making 1+ ions)

The energy required to remove one mole of electrons from 1 mole of the gaseous atoms

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

24
Q

what is 1st IE dependant on

A

Nuclear charge more = increase IE

Shielding more = decrease in IE

Distance more = decrease in IE

25
Q

what are the trends of 1st IE as it goes down a group

A

decrease

Because nuclear charge increases, however shielding sand distance of the e from the nucleus increases

Which lowers the effective charge on the nucleus

Decreases the attraction between the nucleus and outer e

Lowers the energy required to remove the outer e

26
Q

what are the trends of 1st IE going across a period

A

general increase

As nuclear charge increases, there is no change in the amount of shielding/ distance of the outer e from the nucleus

Attraction between the outer e and nucleus increases

more energy need to remove the e

27
Q

what are the exceptions to trends of 1st IE going across a period

A

between group 2/3

EG. Be/B

This is because the outer electron in B is in the 2p electron orbitals and the outer e in Be is in 2s orbital

The e in the 2p orbital has the higher e

Therefore is required to remove it

AND between groups 5/6

EG N/O

The outer e in O is paired with another in the 2p orbital

the outer electron in N is not paired

Repulsion between the paired electrons in o means that less energy is required to remove it

This is because e it is easiest remove due to shielding makes a full s orbital

Easier to remove due to repulsion between paired e

28
Q

what is successive ionisation energy

A

the energy required to remove es one y one from the same atom

Eg. 2nd ie : X+(g) => X2+(g) + e-

3rd ie: X2+(g) => X3+(g) + e-

29
Q

what is trend of successive ionisation energies

A

General increase in ie due to increasing effective charge on the nucleus

30
Q

describe what is going on in these photos

and how to figure out which group of elements the graph is describing

A

Large jumps caused by the e being taken from an energy level that’s closer to the nucleus

ie DECREASED distance + DECREASED shielding

Therefore stronger attraction

Pattern in group 1: large jump between successive ie 1+2

group 2: large jump between successive ie 2+3

etc…

chem (13 decks)

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