Atomic Structure

Question 1

Define Isotope

Answer 1

Same number of protons but a different number of neutrons

Question 2

Define ion

Answer 2

A charged particle with more/fewer electrons than protons

Question 3

In the periodic table symbols what are A and Z

Answer 3

A is the mass number
Z is the atomic number

Question 3

Define Nucleon

Answer 3

Particles in the nucleus

Question 4

Define Element

Answer 4

A chemical (molecule or atoms) made up of 1 type of atom, all with the same number of protons

Question 5

What’s the equation to calculate the number of neutrons?

Answer 5

N = A - Z

Where A is the mass number and Z is the atomic number

Question 6

What’re the 2 points you need to make for the model answer about the models of the atom

Answer 6

The current model has:

Neutrons and Protons in the nucleus,

Electrons orbit the nucleus in different energy levels

Question 7

Define Relative Molecular Mass

Answer 7

The average weighed mass of one molecule compared to 1/12th the mass of one atom of carbon 12

Question 7

Define Relative Atomic Mass

Answer 7

The average weighed mass of one atom compared to 1/12th the mass of one atom of carbon 12

Question 7

What’s the equation to calculate relative atomic mass?

Answer 7

𝑅𝐴𝑀= (∑(𝑚𝑎𝑠𝑠 𝑥 𝑎𝑏𝑢𝑛𝑑𝑎𝑛𝑐𝑒))/(𝑡𝑜𝑡𝑎𝑙 𝑎𝑏𝑢𝑛𝑑𝑎𝑛𝑐𝑒)

Total abundance is all abundances added together

Question 8

What should be done if there are 2 unkown abundances in a RAM calculation?

Scaffold

Answer 8

Solve simultaneously, by creating an equation showing the left over %s in terms of x+y and rearranging

Question 9

Model Answer describing Electron Impact

Answer 9

(for atoms/small molecules)
High energy electrons
From electron gun.
Fired at sample.
Knocks off one electron.
Has to happen in the gas phase.

Question 10

Equation for electron impact with state symbols

Answer 10

M(g) –> M(g)+ + e-

Question 11

Model Answer for Electrospray

Answer 11

Sample dissolved in volatile polar solvent
Injected as an aerosol through needle
Needle has a high positive charge
Sample gains a H+ ion

Question 12

Equation for Electrospray

With state symbols

Answer 12

M(g)+ H^+(g) –> MH^+(g)

Question 13

Model Answer describing Acceleration

Answer 13

Positive ions are accelerated by a negative electric field
To a constant kinetic energy

Question 14

Ion Drift Model Answer

Answer 14

The positive ions with smaller m/z values will have the same kinetic energy as those with larger m/z and so will move faster as they have less mass, so have more velocity. The heavier particles move slower. The ions are separated by different flight times.

Question 15

Detection model Answer

Answer 15

For each isotope the mass spectrometer can measure a m/z (mass/charge ratio) and an abundance. Each ion of the same mass hits the detector plate at the same time.
Each ion gains an electron.
This generates a current that is measured. The current is proportional to abundance

Question 16

What is a molecular ion peak? What do they show?

Answer 16

Molecular ion peak is the peak furthest to the right that isn’t tiny.
Molecular ion peak’s m/z=molecules Mr

Question 17

What does Time of Flight mass spectrometry measure?

Answer 17

ToF mass spec measures 2 properties of compounds (and their ions) mass/charge ratio, called m/z and abundance

Mass/charge ratio is the relative mass of the ionised chemical compared to the positive charge of the molecule

In ToF mass spec the charge of the ions involved is often +1 and there is little fragmentation

Question 18

What’s the equation that links v, d and t?

Answer 18

v=d/t

Question 19

What’s the substitution equation for KE and d and t?

Answer 19

Question 20

What’s the equation to calculate the mass of an atom?

Answer 20

mass of 1 atom = (Ar/1000)/L

Question 21

Equation for calculating the time of 2 different particles with different masses?

Answer 21

mx/tx^2=my/ty^2

Question 22

What are the 4 types of orbital?

Answer 22

s, p, d, f

Question 23

Where are the s, p, d and f blocks?

Answer 23

Question 24

Model Answer describing s and d orbitals

Answer 24

s fills and empties before d

Question 25

What are the rules for filling orbitals?

Answer 25

Electrons enter the lowest available energy level

When in orbitals of equal energy, electrons will try to remain unpaired

No two electrons can have the same four quantum numbers.

Question 26

Define First Ionisation Energy

Answer 26

The minimum energy required to remove 1 mole of electrons from 1 mole of gaseous ions

Question 27

What three factors affect ionisation energy?

Answer 27

Distance from nucleus,
Nuclear Charge,
Shielding by electrons,

Question 28

What is shielding?

Answer 28

When the number of inner electrons is greater, they shelter the outermost electron from the nucleus, allowing it to neglect the nuclear pull to some extent.

Question 29

Model Answer describing atomic radius down a group

Answer 29

Down a group atomic radius increases because, whilst the nuclear charge (number of protons) increases, the energy levels and shielding increase more

Question 30

Model answer describing atomic radius trends across a period

Answer 30

Across a period the atomic radius decreases because the nuclear charge increases and the energy level and shielding stay the same.

Question 31

Model Answer - First ionisation energy down a group

Answer 31

larger atomic radius

More shielding

Therefore weaker attraction from nucleus to electron in outer shell

Question 32

Model Answer first ionisation energy general trend across a period

Answer 32

Across a period:
Increased nuclear charge (i.e. more protons)
Smaller atomic radius
No change in Shielding
Therefore stronger attraction from nucleus to electron in outer shell

Question 33

First ionisation energy trend, Graph

Answer 33

Question 34

Model answer reason for deviation between Mg and Al in first ionisation energy

Answer 34

First electron in 3p which is higher in
energy

Question 35

Model Answer - Reason for deviation for S and P in first ionisation energy

Answer 35

S is lower than expected because it has the first spin pair repulsion in 3p

Question 36

Model Answer - Describing identifying an element from successive ionisation energy

Use X and Y as the numbers of the ionisation

Answer 36

There is a large jump between X and Y. This is because the lower energy level are much closer to the nucleus and less shielded so have a stronger attraction to nucleus requiring more energy to remove them.