Relative Atomic Mass And The Mass Spectrometer

Question 1

Who developed the alpha scattering experiment

Answer 1

Earnest rutherford

Question 2

Define relative atomic mass

Answer 2

The average mass of an atom of an element / mass of 1/12 mass of 1 atom of carbon 12

Question 3

Define relative isotopic mass and molecular

Answer 3

Mass of 1 atom of an isotope / 1/12 of one atom of carbon 12 (same for molecular)

Question 4

What is the first step in the mass spectrometer

Answer 4

Ionisation

Question 5

Describe electrospray ionisation

Answer 5

High voltage is applied to the sample causing each atom to gain h+ions sample is turned into a gas made of positive ions

Question 6

Describe electron impact ionisation

Answer 6

Sample is vaporised and electron gun is used to fire high energy electrons which knocks off an electron from the atoms

Question 7

What is the second stage of the mass spectrometer called

Answer 7

Acceleration

Question 8

Describe acceleration in 3 steps

Answer 8

1- ions are accelerated by electric field
2- have the same kinetic energy
3- lighter ions will travel through faster

Question 9

What is the 3rd stage of the mass spectrometer

Answer 9

Ion drift

Question 10

What is absent in ion drift

Answer 10

Electric field

Question 11

What is the last stage of the mass spectrometer

Answer 11

Detection

Question 12

Describe detection in 3 steps

Answer 12

1.Lighter ions travel at higher speeds
2. Detector detects charged particles
3. Spike in electric current is produced

Question 13

What is the equation for working out relative atomic mass

Answer 13

(% of an isotope x mass ) / total percentagEs

Question 14

What is the principal quantity number

Answer 14

The name given to the shell number

Question 15

How many electrons can the s shell hold

Answer 15

2

Question 16

How many electrons can the p shell hold

Answer 16

6

Question 17

How many electrons can the d shell hold

Answer 17

10

Question 18

Name the 4 different blocks of elements

Answer 18

S p d f

Question 19

What are the sub shells in increasing energy up to 4p

Answer 19

1s 2s 2p 3s 3p 4s 3d 4p

Question 20

Which groups of the periodic table do atoms tend to form negative ions

Answer 20

P block

Question 21

Define first ionisation energy

Answer 21

The energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms from one mole of gaseous 1 + ions

Question 22

What does first ionisation energy mean

Answer 22

How much energy it take to take the first electron off the atom

Question 23

What is the equation for first and second ionisation energy

Answer 23

First - O(g) = O+(g) + e-

Question 24

Name the factors affecting ionisation energy

Answer 24

Nuclear charge, distance from nucleus, shielding

Question 25

Describe how nuclear charge affects ionisation energy

Answer 25

The more protons you have the more positively charged the nucleus is and the stronger the attraction between the electrons and the nucleus

Question 26

Describe how distance from nucleus affects ionisation energy

Answer 26

The closer an electron is to the nucleus the stronger the attraction

Question 27

How does shielding affect ionisation energy

Answer 27

More shielding means lower ionisation energy as there is more layers blocking attraction to nucleus

Question 28

What does a high ionisation energy mean

Answer 28

There is stronger attraction to the nucleus so requires more energy to remove the electron

Question 29

What happens to first ionisation energy as you go down a group and why

Answer 29

It decreases bigger nuclear radius so more shielding

Question 30

What usually happens to first ionisation energy as you go across a period

Answer 30

Increases generally

Question 31

Describe the trend in ionisation energies as you go down group 2

Answer 31

As you go down group 2 each atom has an extra electron shell meaning more shielding. This means it has a lower ionisation energy.

Question 32

Why is there a drop between group 2 and group 3 with ionisation energy

Answer 32

Aluminiums outer electron is a 3p orbital instead of 3s which has slightly higher energy

Question 33

What is the drop in group 5 and 6 due to

Answer 33

Electron replusion

Question 34

Why is the second ionisation energy of silicon lower then the second ionisation of aluminium

Answer 34

Electron is moved from a higher orbital

Question 35

Why is the first ionisation if sulfur less then that of phosphorus

Answer 35

Paired electrons in 3p orbital so they repel

Question 36

Whatis the trend ionisation energies for group between aluminium and argon

Answer 36

Increases as increase in nuclear charge so similar shielding

Question 37

How is the relative molecular mass of a covalent compound obtained from mass spectrum

Answer 37

Highest m/z value

Question 38

Why might relative atomic mass of a sample be diff to relative atomic mass on the periodic table

Answer 38

Other isotopes are present in periodic table number

Question 39

Why must ions be ionised in the mass spectrometer

Answer 39

So they can be accelerated by electric field

Question 40

Why is the first ionisation energy of magnesium higher then sodium

Answer 40

Increase in nuclear charge and similar sheilding

Question 41

Define electronegativity

Answer 41

Ability of an atom to attract electrons in a covalent bond

Question 42

Explain why certain elements are classified as p block

Answer 42

Outer electron is in the orbital p

Question 43

Give two reasons why we ionise isotopes before putting it into mass spec

Answer 43

So they can be accelerated

Ions create a current when hitting the detector

Question 44

Where does s block finish

Answer 44

Berylium(Be)

Question 45

Where does d block start and end

Answer 45

Starts at scandium (Sc) and ends at Zinc (Zn)

Question 46

Where does P block start and end

Answer 46

Starts at boron (B)

Question 47

State the meaning of the term periodicity

Answer 47

Repeat patterns in periodic table