Atomic structure

Question 1

Define the term relative atomic mass?

Answer 1

Average mass of an atom of an element, which is relative to 1/12 of the mass of Carbon-12

Question 2

Define first ionisation energy?

Answer 2

Amount of energy needed to remove a mole of electrons from a mole of atoms, in a gaseous state

Question 3

What is happening to the radius across a period?

Answer 3

Shielding is the same, nuclear charge increases so stronger electrostatic attraction between nucleus + outermost electrons, radius decreases

Question 4

What is happening to the IE across a period?

Answer 4

Shielding is the same, nuclear charge increases so stronger electrostatic attraction between nucleus + outermost electrons, so more energy required to remove the outermost electron so IE increases

Question 5

What is happening to the IE down a group?

Answer 5

Shielding increases, less electrostatic attraction between nucleus + outermost electrons, so less energy required to remove the outermost electron so IE increases

Question 6

Which is smaller, Na+ or Mg?

Answer 6

Na+ ion has less shells
Its electron is closer to the nucleus + there’s less shielding
So the outer electrons are more strongly attracted to the nucleus

Question 7

Why is it necessary to ionise the mixture?

Answer 7

Acceleration + detection

Question 8

How are the ions accelerated?

Answer 8

Positive ions accelerate towards the negatively charged plate

Question 9

Why do the different ions separate in the flight tube?

Answer 9

Same kinetic energy, different velocities
Heavier particles travel slower

Question 10

Why is the inside of the machine a vacuum?

Answer 10

So there particles can’t interfere with the ion beam made from the sample

Question 11

How are the ions detected + how is their abundance measured?

Answer 11

Ions hit the detector + gain an electron
This generates a current proportional to the abundance

Question 12

Name the ionisation method when a particle gains a proton to form an ion?

Answer 12

Electrospray

Question 13

What are the 2 measurement made by the mass spectrometer?

Answer 13

M/Z ratio
Relative abundance

Question 14

How are ions formed via electron impact?

Answer 14

• Sample is vaporised
• High-energy electrons are fired at sample from an electron gun
• One electron is knocked off each particle

Question 15

How are ions formed via electrospray ionisation?

Answer 15

• Sample is dissolved in a volatile solvent
• Sample is injected through a needle at high voltage
• Sample is ionised by gaining a proton

Question 16

A mass spectrum shows the measurement of M/Z ratio + relative abundance. Which axis represents M/Z ratio?

Answer 16

X Axis

Question 17

Equation of the element P during electro spray ionisation?

Answer 17

P + H+ ——> PH+

Question 18

State, in terms of electrons, the meaning of the term oxidising agent?

Answer 18

Electron acceptor

Question 19

State, in terms of electrons, the meaning of the term reducing agent?

Answer 19

Electron donor