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AS CHEMISTRY > ATOMIC STRUCTURE > Flashcards

ATOMIC STRUCTURE Flashcards

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1
Q

Lost the 3 sub atomic particles

A

Proton
Neutron
Electron

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2
Q

What is the relative mass of an electron

A

1/1840

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3
Q

Define atomic number

A

The number of protons in the nucleus

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4
Q

Define mass number

A

The number of protons and neutrons in the atom

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5
Q

Define isotope

A

Atoms with the same number of protons but different numbers of neutrons

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6
Q

Outline the features of isotopes

A

Similar chemical properties
Due to same electronic structure

Slightly varying physical properties
Due to different masses

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7
Q

Define the use of a time of flight mass spectrometer

A

Determine I stopped present in a sample of an element

Identify elements

Calculate relative atomic mass

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8
Q

What are the 4 steps in a mass spectrometer

A

Ionisation
Acceleration
Flight tube
Detection

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9
Q

Outline electron impact ionisation

A

Vapour used sample injected at low pressure

Electron gun fires high energy electrons at sample

Outer electron is knocked out

Positive ion is formed with different charges

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10
Q

When is electron impact used?

A

Elements and substances with low formula mass

As larger organic molecules can fragment

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11
Q

Outline electro spray ionisation

A

Dissolve sample in volatile polar solvent

Object through hypodermic needle giving fine mist or aerosol with high voltage

Sample molecule gains proton and H+

Solvent evaporates and negative sample H+ ions move toward negative plate

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12
Q

When is electro spray ionisation used

A

Larger organic molecules

Softer conditions prevent fragmentation

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13
Q

Outline acceleration in TofF mass spectrometry

A

Positive ions are accelerated

By an electric field

To a constant kinetic energy

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14
Q

Why are ions accelerated in TofF spectrometry

A

Same kinetic energy

Different mass

Velocity depends on mass

Lighter particles have faster velocity

Heavier particles have slower velocity

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15
Q

Outline what happens in the flight tube

A

Positive ions with smaller m/z have same kinetic energy as larger m/z

So they move faster

Heavier particles take longer in the drift area

Ions are distinguished by different flight times

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16
Q

Outline detection in a TofF mass spectrometer

A

Ions generate small current at detector plate

Linked to computer for analysis

Current is proportional to abundance of species

Due to electron transfer to ions

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17
Q

What can a mass spectrometer measure

A

M/z (mass to charge ratio)

Abundance

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18
Q

What happens if two electrons are removed

A

Halves the mass value

Due to m/z ratio

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19
Q

Outline the equation for calculating relative atomic mass

from percentage abundance

A

(Sum of) isotopic mass x % abundance

all over 100(%)

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20
Q

Outline the equation for calculating relative atomic mass

From relative abundance

A

(Sum of) isotopic mass x relative abundance

All over total relative abundance

21
Q

How do diatomic molecules effect mass spectrometry

A

Cl and Br have two isotopes

The two isotope masses add together to create a combined mass

Creating three peaks for two isotopes

Eg Cl35 + Cl35, Cl35 + Cl37, Cl37 + Cl37

22
Q

What causes the different relative atomic mass on other planets

A

Different abundance of isotopes

Different variants of isotopes

23
Q

How can electron impact ionisation effect the appearance of the mass spectrum for a larger ion

A

Fragmentation occurs

Creating several peaks

The largest m/z is the full molecule

Called the parent ion or molecular ion

24
Q

How does measuring the Mr with electro spray ionisation differ

A

Remove one for the mass of the H+ ion

25
Q

What are the su levels in the 4th principle level

A

4s, 4p, 4d, 4f

26
Q

How many electrons can each sub level hold

A

S - 2 pairs
P - 3 pairs
D - 5 pairs
F - 7 pairs

27
Q

What does an orbital represent

A

The mathematical probability

of finding an electron at any point

within a certain spatial distribution around the nucleus

28
Q

How does 4s act compared to 3d

A

4s gas less energy than 3D

So 4s is filled first

4s is further from the nucleus than 3d

So 4s is lost first

29
Q

Outline chromium a electronic structure

A

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

30
Q

Outline coppers electronic structure

A

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

31
Q

Why do chromium and copper have different electronic structures

A

To minimise repulsion

4s2 pair has more repulsion

Than 3d5/3d10

32
Q

Define first ionisation energy

A

The enthalpy change

when one mole of gaseous atoms

forms one mole of gaseous ions

with a single positive charge

33
Q

Define second ionisation energy

A

The enthalpy change

When one mole of gaseous ions

With a single positive charge

Forms one mole of gaseous ions

With a double positive charge

34
Q

First ionisation equation

A

H(g) > H+(g) + e-

Ti+(g) > Ti2+(g) + e-

35
Q

What are the factors affecting ionisation energy

A

Proton number

Atomic radius

Shielding

36
Q

Outline how proton number effects ionisation energy

A

More protons

Greater attraction of e- to nucleus

E- harder to lose

37
Q

Outline how atomic radius effects ionisation energy

A

Bigger atom

Electron further from the nucleus

Less attraction

Electron easier lost

38
Q

Outline how shielding effects ionisation energy

A

More shielding

Electron more repelled

Electron further from nucleus

Electron easier lost

39
Q

Why are successive ionisation energies always larger

A

Second ionisation is bigger than first

Positive ion is formed in first ionisation

Ion increases attraction to the nucleus

Increasing the energy required to remove more electrons

40
Q

What causes large jumps between successive ionisation energies

A

a change in shell

The latter energy is higher

Because it is closer to the nucleus

As it is in a different energy she’ll

41
Q

Define periodicity

A

A repeating pattern across a period

42
Q

Outline the shape of first ionisation energy from H to Ne

A

Large jump from H to He

Larger drop from He to Li

Small jump from Li to Be

Slight drop from Be to B

Increase from B to N

Slight drop from N to O

Increased from O to Ne

43
Q

Outline the shape of first ionisation energy from Ne to Ar

A

Large drop from Ne to Na

Small jump from Na to Mg

Small drop from Mg to ask

Increase from Al to P

Slight drop from P to S

Increase from S to Ar

44
Q

Outline why helium ahs the largest first ionisation energy

A

First electron is in first shell closest to nucleus

No shielding

More protons than H

45
Q

Why do first ionisation energies decrease down the group

A

Outer electrons are further from the nucleus (larger radius)

More shielding

Attraction becomes smaller

Electron easier lost

46
Q

Why is there a general increase in fest ionisation energy across a period

A

Electrons are added to the same shell across the period

Same radius size

Same shielding more protons

Larger attraction of e- to nucleus

47
Q

Why is there a drop between Na and Ne

A

Na has outer electron in 3s shell

3s further from nucleus and more shielded

Has outer electron easier to remove

48
Q

Why is there a drop between Mg and Al

A

Al filling 3p sub shell

Mg has outer electrons in 3s sub shell

3p are easier to remove

because they have higher energy

And are slightly shielded by 3s electrons

49
Q

Why is there a small drop from P to S

A

S has 4 electrons in 3p sub shell

Creating a pair of electrons

This creates a slight repulsion

Making the electron easier to remove

AS CHEMISTRY (17 decks)

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