Atomic Structure Flashcards

1
Q

Proton relative mass and charge

A

1 and +1

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2
Q

Neutron

A

1 and 0

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3
Q

Electron

A

1/1840 and -1

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4
Q

What is the atomic number

A

Number of protons in nucleus

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5
Q

Mass number

A

Total number of protons and neutrons

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6
Q

What are isotopes

A

Atoms with same number of protons but different number of neutrons

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7
Q

What are isotopes

A

Atoms with same number of protons but different number of neutrons

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8
Q

Why do isotopes have similar chemical properties but different physical properties

A

They have the same chemical properties as they have the same electronic structure but different physical properties as they have different masses

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9
Q

What is the use of a mass spectrometer

A

Identify elements
Determine relative molecular mass

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10
Q

What is the condition for mass spectrometer

A

VACCUM
If not, air particles would ionise and register on detector

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11
Q

4 steps of a mass spectrometer

A

Ionisation - broken down into electron impact and electron spray
Acceleration
Drift
Detection

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12
Q

Explain ionisation in terms of electron impact

A

Vaporised sample is injected at low pressure.
Electron gun fires high energy electrons in the sample.
This knocks out an electron which forms a positive ion with different charges

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13
Q

Explain ionisation in terms of electron spray

A

Sample is dissolved in a volatile polar solvent
Sample is injected through a fine hypodermic needle which produces a fine mist /aerosol
Needles tip has high voltage so as molecule passes through it gains a proton, producing MH+
Solvent evaporates and MH+ ion moves towards negative plate

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14
Q

What is fragmentation

A

When a molecular ion breaks into smaller ions/neutral ions/radicals ~ fragments

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15
Q

What is fragmentation

A

When a molecular ion breaks into smaller ions/neutral ions/radicals ~ fragments

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16
Q

What is electron impact used for and does it cause fragmentation

A

Elements/ substances with low formula mass, it can cause fragmentation

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17
Q

What is electron spray used for and does it cause fragmentation

A

Larger organic molecules
No fragmentation

18
Q

Explain acceleration

A

Positive ions accelerated by an electric field to a constant velocity

19
Q

What do all particles have in similar and what is different

A

All particles have the same kinetic energy bur different velocity as the velocity depends on the mass

20
Q

Lighter particles have

A

Fasted velocity

21
Q

Heavier particles have

A

Slower velocity

22
Q

Explain drift

A

Ions spread out by velocity, heavier paricles take longer positive partivked move faster
Ions are distinguished by flight times

23
Q

Explain detection

A

Ions reach detector
Generate a small current which is produced by the positive ions gaining an electron
Current is fed to computer for analysis
Size or current is proportional to abundance

24
Q

What is relative atomic mass

A

Average mass of an atom of an element relevant to 1/12 of the RAM of carbon-12

25
Q

What is the peak called which is due to electron impact ionisation and what does it equal

A

Molecular ion
It is equal to the relative molecular mass of the molecule, it is also the peak with largest MZ

26
Q

What is the peak equal to when a molecule is put through electro spray ionisation

A

It is equal to the mass of the MH+ ion
(Subtract 1 from the MR)

27
Q

What are the subshells called?

A

S P D F

28
Q

How many electrons can S hold?

A

Two

29
Q

Electrons in p

A

6

30
Q

Electrons in d

A

10

31
Q

What is the definition for first IE and give an equation for Hydrogen

A

It is the enthalpy change when one mole of gaseous atoms form one mole of gaseous ions with a single positive charge
H(g)———> H+(g) + e-

32
Q

What are the 3 main factors which affect IE

A
  1. Nucleus attraction
  2. Distance of nucleus and electrons
  3. Shielding
33
Q

Explain attraction of nucleus

A

More protons in the nucleus means that there is a greater attraction

34
Q

Explain how the distance of the electron from the nucleus effect i.e.

A

The big of the atom, the further the outer electrons are from the nucleus which weakens the attraction to the nucleus

35
Q

Explain how shielding affects Ie

A

The attraction between outer electrons and the nucleus decreases as the number of electrons between them and the nucleus increases

36
Q

Why are successive ionisation energies always larger?

A

The second ionisation of an element is always bigger than the first ionisation energy. This is because when the first election is removed, a positive ion is formed which increases the attraction on the remaining electrons so energy required to remove the next electron is larger

37
Q

Why does first Ie decrease down a group?

A

As you go down the group, I’ll tell electrons are found in shell further away from the nucleus and are more shielded so the attraction becomes smaller

38
Q

Why does first Ie decrease down a group?

A

As you go down the group, I’ll tell electrons are found in shell further away from the nucleus and are more shielded so the attraction becomes smaller

39
Q

Why is a general increase in first i.e. across a period?

A

Are you go across a period? Electrons are being added to the same shell which has the same distance from the nucleus and same shielding affect the number of protons increase which makes the attraction of the nucleus greater

40
Q

Why has NA got a lower first ie than neon?

A

NA has its outer electrons on the 3s sub shell which is further from the nucleus and more shielded so it’s outer of electron is easier to remove and has a lower first ie

41
Q

Why is this small drop from MG to Al

A

Al fills. 3p sub shell whereas MG fails the 3s subshell electrons in 3p subshell are easier to remove as the 3P electrons are higher in energy and are also slightly shielded by 3s electrons

42
Q

Why is there a small drop from P to s

A

Sulfur has a lower IE than P because the electron pour is un 3P orbital which repel each other therefore easier to remove