1P-Atomic Structure

Question 1

What is a mass spectrometer used for

Answer 1

To analyse elements

Question 2

What are the principals of how a time of flight mass spectrometer works (VIADD)

Answer 2

Vaporisation (electron impact only)
Ionisation
Acceleration
Ion drift
Detection

Question 3

What happens in the electron impact method of ionisation

Answer 3

An electron is fired at gaseous particles using an electron gun
Most ions created have a +1 charge as one electron is knocked off

Question 4

What happens in the electron spray method of ionisation

Answer 4

Sample is dissolved in a volatile solvent
Forced through a high voltage fine needle producing a fine mist
Each atom gains a proton as it leaves the needle
Final mass is 1 more due to this

Question 5

What happens during acceleration

Answer 5

Positive ions are accelerated using an electric field, have the same KE
Velocity of particle depends on mass, lighter ones travel faster

Question 6

What happens during ion drift

Answer 6

The +ve charged particles travel through a tube
Time of flight depends velocity, which depends on mass

Question 7

What happens during detection

Answer 7

+ve ions hit a -ve charged plate, +ve ions are discharged, movement of electrons induces electric current
Size of current measured is proportional to abundance

Question 8

When is the electron impact method used

Answer 8

For compounds with a low RFM, causes fragmentation

Question 9

When is the electro spray method used

Answer 9

For molecules with a high RFM

Question 10

How has atomic structure evolved over time

Answer 10

Plum pudding- sphere of +ve charge, -ve charges distributed evenly within
Alpha particle experiment- small dense centre (nucleus), electrons in shells

Question 11

Relative masses and charges of subatomic particles

Answer 11

Proton- M1 C+1
Electron- M1/1860 C-1
Neutron- M1 C0

Question 12

What letter represents the mass number

Answer 12

A

Question 13

What letter represents the number of protons

Answer 13

Z

Question 14

Trend of ionisation in period 3 (Na-Ar)

Answer 14

Ionisation energy increases, number of protons increase, more attraction to nucleus, harder to remove electrons
However decrease of ionisation energy from magnesium to aluminium, aluminium had 3p1 shell, higher energy level, less energy needed to remove that electron

Question 15

Trend in ionisation in group 2 (Be-Ba)

Answer 15

Decrease in ionisation energy down group 2, energy levels become higher, valence electron further from nucleus
Number of protons do increase however due to the shielding effect from inner electrons there is less attraction.

Question 16

What is ionisation energy

Answer 16

The energy taken to remove one mole of electrons from one mole of gaseous atoms
Measure in Kj/mol

Question 17

An equation for first and successive ionisation energies

Answer 17

First IE Na (g) —> Na + (g) + e-
Second IE Na + (g) —> Na 2+ (g) + e-

Question 18

How to calculate relative molecular mass from a mass spectrum

Answer 18

A substantial peak with the highest m/z value

Question 19

Electronic config of Cr

Answer 19

1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d5

Question 20

Electronic config of Cu

Answer 20

1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d10

Question 21

What’s the difference in electronic config for most transition metals

Answer 21

3d sub shell empties and fills before the 4s

Question 22

Equation for converting relative atomic mass into mass with avogadros number

Answer 22

RAM/avogadros constant = mass