atomic structure

• what is relative atomic mass?

  average mass of an atom of an element compared to 1/12th the mass of a carbon-12 taking into account isotopes
• what is the relative charge and mass of a proton?

  charge = +1 mass = 1
• what is the relative charge and mass of a neutron?

  charge = 0 mass = 1
• what is the charge and mass of an electron?

  charge = -1 mass = 1/1840
• what are the different types of electron orbitals?

  s,p and d
• what are electron orbitals?

  clouds of negative charge where electrons are held
• what are the orders of the different blocks?

  s, p, d
• what is the electron configuration for C?

  1s2 2s2 2p2
• what does mass spectrometer do?


  separates the sample by their mass and electrical charge
• what are the 2 types of ionisation in mass spec?

  electron impact and electrospray ionisation
• what is electron impact ionisation?

  sample analysed is vapourised and hit with high intensity electrons, knocking off an electron, come from a hot wire filament electron gun
• what kind of sample is used for electron impact ionisation?

  low formula mass, may cause fragmentation
• what is electrospray ionisation?

  sample dissolved in volatile solvent and injected through a hypodermic needle to form a mist, needle tip is attached to positive terminal voltage supply so particles gain a proton from the solvent
• what type of solvent is used for electrospray ionisation?

  high molecular mass, rarely leads to fragmentation
• what is acceleration in mass spec?

  positive ions are accelerated by a plate in a negative electric field so they have the same kinetic energy
• what is flight tube/ion drift in mass spec?

  all particles have the same kinectic energy, lighter particles move through tube faster than heavier ones
• what is detection in mass spec?

  ions hit detector plate, gaining electron and producing an electric current, bigger the ion the larger the current measured will be