1.5 4.Bohr model - Improvement Spiral down and
collapse. 4 rules Fixed frequency. Present.
2 Relative Mass.
2.1 Relative masses are masses of atoms compared to
2.2 Relative masses can be using a mass spectrometer.
Method is called Mass spectorscopy.
2.2.1 Mass spectrometer consists of 4 stages:
Vaporisation , Ionisation , acceleration ,
18.104.22.168 Vaporisation : sample is turned into gass using electrical heater.
22.214.171.124 Ionisation: Gas particles are bombarded with high energy
electrons. electrons are knocked of the
particles turning them posi ions.
126.96.36.199 Accleration: Posi ions are accelrated by an
eletric field.Given the same kinectic energy.
188.8.131.52 Detection: Time taken to reach the detector is measured. Depends on
the ions mass and charge- light highly charged ions will reah first and
the oppisite after.
184.108.40.206 After each sample is analysed a mass spectrum is produced.
220.127.116.11.1 Mass specturm Y axis =
abundance X axis =
Mass charge ratio.
2.3 Mass spectrometry can be used to find Mr. But
bombarding molecules with electrons causes them to
break into fragments .This will show on the MS making
a fragmentation pattern. These can be used to indentify
molecules and their structure.
3 Nuclear Radiation.
3.1 Alpha - Strong ionising ability -
slight deflection in electric field.
3.2 Beta-Moderate ionising ability - large
deflection in electric field.
3.3 Radioactive dating.
3.3.1 Invovles measuring how much a Particular
carbon there is in plant remains ect.
3.3.2 All living things have the same % of C14 But as they die
tthe % begins to decrease as C14 decays. Less % older
it must be. Approx age.