Atomic Structure

Question 1

Proton relative mass and charge

Answer 1

1 and +1

Question 2

Neutron

Answer 2

1 and 0

Question 3

Electron

Answer 3

1/1840 and -1

Question 4

What is the atomic number

Answer 4

Number of protons in nucleus

Question 5

Mass number

Answer 5

Total number of protons and neutrons

Question 6

What are isotopes

Answer 6

Atoms with same number of protons but different number of neutrons

Question 7

What are isotopes

Answer 7

Atoms with same number of protons but different number of neutrons

Question 8

Why do isotopes have similar chemical properties but different physical properties

Answer 8

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

Question 9

What is the use of a mass spectrometer

Answer 9

Identify elements
Determine relative molecular mass

Question 10

What is the condition for mass spectrometer

Answer 10

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

Question 11

4 steps of a mass spectrometer

Answer 11

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

Question 12

Explain ionisation in terms of electron impact

Answer 12

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

Question 13

Explain ionisation in terms of electron spray

Answer 13

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

Question 14

What is fragmentation

Answer 14

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

Question 15

What is fragmentation

Answer 15

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

Question 16

What is electron impact used for and does it cause fragmentation

Answer 16

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

Question 17

What is electron spray used for and does it cause fragmentation

Answer 17

Larger organic molecules
No fragmentation

Question 18

Explain acceleration

Answer 18

Positive ions accelerated by an electric field to a constant velocity

Question 19

What do all particles have in similar and what is different

Answer 19

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

Question 20

Lighter particles have

Answer 20

Fasted velocity

Question 21

Heavier particles have

Answer 21

Slower velocity

Question 22

Explain drift

Answer 22

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

Question 23

Explain detection

Answer 23

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

Question 24

What is relative atomic mass

Answer 24

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

Question 25

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

Answer 25

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

Question 26

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

Answer 26

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

Question 27

What are the subshells called?

Answer 27

S P D F

Question 28

How many electrons can S hold?

Answer 28

Two

Question 29

Electrons in p

Answer 29

6

Question 30

Electrons in d

Answer 30

10

Question 31

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

Answer 31

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-

Question 32

What are the 3 main factors which affect IE

Answer 32

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

Question 33

Explain attraction of nucleus

Answer 33

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

Question 34

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

Answer 34

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

Question 35

Explain how shielding affects Ie

Answer 35

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

Question 36

Why are successive ionisation energies always larger?

Answer 36

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

Question 37

Why does first Ie decrease down a group?

Answer 37

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

Question 38

Why does first Ie decrease down a group?

Answer 38

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

Question 39

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

Answer 39

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

Question 40

Why has NA got a lower first ie than neon?

Answer 40

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

Question 41

Why is this small drop from MG to Al

Answer 41

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

Question 42

Why is there a small drop from P to s

Answer 42

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