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NUCLEAR FORCE: The force which holds together neutrons and protons.
ELECTROSTATIC FORCE: The force that holds the electrons and protons together and overcomes
the repulsion of the protons (with another proton) in the nucleus.
NUCLEONS: Protons and neutrons.
Electron shells: 2, 8, 18
ATOMIC/PROTON NUMBER, Z= number of protons.
MASS NUMBER, A= Number of protons + number of neutrons.
ISOTOPES= Atoms with the same number of protons but different number of neutrons.
Different isotopes of the same element react chemically in the exact same way due to same
electronic configuration in outer shell.
Atoms of different isotopes of the same element vary in mass number because of the different
number of neutrons in their nuclei.
Sometimes when isotopes are unstable and give off radioactivity.
Each radioactive isotope decays at a rate measured by its half life. This is the time taken for half of
its radioactivity to decay.
Determines relative atomic mass.
Instrument is kept under a HIGH VACUUM so that the ions do not collide with air molecules
which could potentially stop them from reaching the detector.
The sample is investigated in the GASEOUS STATE (gas/volatile liquid it is injected directly,
solids are vaporised)
A beam of electrons from an electron gun knocks out electrons from
IONISATION atoms in the molecules to form positive ions in the gaseous state.
The positive ions are attracted towards negatively charged plates to a
ACCELERATIO high speed.
The speed they reach depends on their mass. (The lighter the mass, the
N faster they go). Some ions form into a beam through a plate slit.
The beam of ions moves into a magnetic field at right angles to its
direction of travel.
The magnetic beam deflects the beam of ions.
DEFLECTION The deflection of the ion depends on the ratio of its mass to charge
(Heaver ions are deflected less, lighter=more)
The stronger the magnetic field, the greater the deflection.
The magnetic field is gradually increased so ions of increasing mass
enter the detector one after another.
DETECTION Ions strike the detector, accept electrons, lose their charge and create
a current which is proportional to the abundance of each ion.
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CALCULATION: (Abundance (%) X mass number)
100(or the total %)
MOLECULAR IONS: An ion which has not broken up during being in the mass spectrometer.
ENERGY LEVELS: Electrons in different shells have differing amounts of energy. Sub levels of
s, p, d, f.
QUANTUM MECHANICS: The probability of finding an electron in a given volume of space
ATOMIC ORBITAL: A region of space around an atomic nucleus where there is a high
probability of finding an electron.…read more