3.1.1 atomic structure

Question 1

relative atomic mass

Answer 1

average mass of an atom of an element measured on a scale where mass of 1 carbon atom is 12

Question 2

isotopes

Answer 2

elements with the same number of protons but different number of neutrons

Question 3

relative isotopic mass

Answer 3

mass of an isotope of an element measured on scale which mass of 1 carbon atom is 12

Question 4

TOF electron impact ionisation

Answer 4

sample is vapourised
x(s)(l) - x(g)
- sample is bombarded with e- with an electron gun, knocking off each atom
x(g)+e- —x+(g)+2e-

Question 5

TOF electrospray ionisation

Answer 5

• sample is dissolved in volatile solvent
• sample is put in a charged needle creating a fine spray of e-
• h+ gained from solvent
  x(g)+H+— xh+(g)

Question 6

TOF acceleration

Answer 6

• charged plates create an electrical field
• ions are accelerated forwards with the same kinetic energy
• happens at different velocities because of the mass
• higher the mass, lower the velocity

Question 7

TOF detection

Answer 7

• negatively charged plate at the end of the TOF tube
• positive ions gain e- at the plate causing electric current
• electric current is monitored and analysed to give a spectra

Question 8

ionisation energy

Answer 8

the minimum amount of energy required to remove 1 mole of e- from 1 mole of atoms in gaseous states