Atomic Structure - Chapter 1

Question 1

What is an atom

Answer 1

It is the smallest part of an element that can exist and still retain all the features of that element

Question 2

What particles make up atoms

Answer 2

Protons
Neutrons
Electrons

Question 3

Relative mass of Protons, Electrons and Neutrons

Answer 3

1
1
1/1800

Question 4

What holds together protons and neutrons

Answer 4

The strong nuclear force

Question 5

what holds the electrons in the energy levels

Answer 5

electrostatic attraction

Question 6

What is the Mass number

Answer 6

Total number of protons and neutrons

Question 7

What is the atomic number

Answer 7

Number of protons

Question 8

What are Isotopes

Answer 8

They are atoms of the same element with the same atomic number but different mass numbers

Question 9

What is relative atomic mass

Answer 9

It is the average mass of an atom of an element on a scale where an atom of carbon 12 is exactly 12

Question 10

what can a mass spectrometer be used to find out about

Answer 10

Relative atomic mass
Relative molecular mass
Relative abundances of iostopes

Question 11

what 4 things happen in a TOF mass spectrometer

Answer 11

ionisation
Acceleration
Ion drift
Detection

Question 12

What happens in ionisation

Answer 12

The sample is ionised by 2 different techniques
Electron impact
Electrospray ionisation

Question 13

What is electron impact

Answer 13

The sample is vaporised and high energy electrons are fired at it
The electrons come from an electron gun, which is a hit filament with a current running through it

Question 14

What does electron impact cause

Answer 14

It knocks off one electron from each particle
Sometimes causes fragmentation

Question 15

What is Electrospray Ionisation

Answer 15

The sample is dissolved in a polar solvent which can act as a source of protons
The solution is pumped through a capillary needle at a high voltage
This causes an aerosol to form and evaporates and the molecule to gain a H+

Question 16

What does Electrospray Ionisation cause

Answer 16

An H+ ion to attach
Doesn’t cause fragmentation

Question 17

What is acceleration

Answer 17

It is the acceleration of the positively charged ions by applying an electrical field to a series of plates
The electric field gives the same kinetic energy to all the ions
The Ions with a lower m/z ratio will accelerate more

Question 18

What is the potential energy equation

Answer 18

PE = q x V

charge on particle x voltage

Question 19

What is the kinetic energy equation

Answer 19

KE= 1/2mv2

Question 20

What is ion drift

Answer 20

All ions leave the electric field with a constant speed ad kinetic energy
The lighter ions will travel to the detector quicker than those with a higher m/z

Question 21

Equation for velocity

Answer 21

v= d/t

Question 22

Equation for the kinetic equation and the velocity equation combined

Answer 22

KE= 1/2 m (d/t)2

Question 23

What links the TOF and m/z ratio

Answer 23

The time of flight is proportional to the mass to charge ratio

Question 24

What is detection

Answer 24

The detector detects the current created when the ions hit it and gain electrons
It records how long they took to pass through the instrument as well as the abundance of each ion

Question 25

How many electrons can fit into energy levels 1 - 4

Answer 25

2
8
18
32

Question 26

What are orbitals

Answer 26

they are sub levels within each energy level
They are a volume of space around a nucleus in which there is a high probability of finding an electron
Each hold a maximum of 2 electrons

Question 27

What are the different types of orbitals

Answer 27

s
p
d
f

Question 28

How many sub orbital pairs are in each type of orbital

Answer 28

s -1
p-3
d-5
f-7

Question 29

what is different about the orbital 4s

Answer 29

It has a lower energy than 3d and so is filled up before 3d

Question 30

What is Aufbau principle

Answer 30

An electron will always fill the available orbital of the lowest energy

Question 31

What is Pauli exclusion principle

Answer 31

Each orbital can hold a maximum of 2 eletrons

Question 32

What is Hund’s rule

Answer 32

Atomic orbitals of the same energy will fill singly with electrons of the same spin before pairing of electrons occurs

Question 33

What is ionisation energy

Answer 33

It is the energy required to remove 1 mole of electrons from 1 mole of an element in its gaseous state

Question 34

How can IE data show which group an element is in

Answer 34

It can be seen as the massive jump in IE

Question 35

Why does ionisation energy decrease as you down the group

Answer 35

The nuclear charge increases as you go down the group
Outermost electrons are in energy levels that are increasingly further away from nucleus
Inner electrons shield outer electrons and allow them to be removed easier

Question 36

What happens to ionisation energy as you go along the period

Answer 36

It increases
Nuclear charge increases
Atomic radius is similar
More shielding

Question 37

Why is 1st IE for aluminium less than Mg’s

Answer 37

Although Al has a higher nuclear charge than Mg, its outermost electron is in a 3p orbital which is further from the nucleus than 3s orbital so less energy required

Question 38

Why is there a slight drop in 1st IE between phosphorus and sulphur

Answer 38

In P orbital, each of the 3 electrons occupies a different 3p orbital whilst in sulphur one iof the 3p orbitals must contain 2 electrons. The repulsion between the electrons makes it easier to remove one

Question 39

Why are the ions charged in TOF mass spectrometer

Answer 39

So the ions will interact and be accelerated by the electric field
Ions create a current when hitting the detector so they can be detected