ATOMS & ISOTOPES
Isotopes are atoms of the same element with different mass numbers ,
due to a difference in neutron numbers .
Relative isotopic mass is the mass of one atom of an isotope ,
relative to
% Of the mass of one carbon -
12 .
Relative atomic mass is the weighted average mass of an atom
of an
element ,
relative to of one carbon-12 isotope .
↳ this is calculated
using relative abundances of each isotope .
MASS SPEC
Mass spec allows us to determine relative atomic masses of elements Icom pounds
Vaporise → the sample can
only travel through the machine as a
gas high vacuum
,
.
ionise → allows
sample to be detected
by magnetic field
-
stream of high
energy electrons removes usually one electron
acceleration → in electric field 71000 V. ion interacts with electric field .
deflection → differs based on mass and charge .
•
: more
more
charged deflection
•
in mass : more deflection
lighter
detection → hit ion detector and produce a current .
↳
magnetic field slowly increased to detect higher masses .
•
mass spec gives relative atomic mass of each atom 1molecule detected ,
and its relative abundance .
•
peaks measure m Iz ratio ( assuming 2=2 I
•
molecular ion peak is the highest mlz value ,
not
largest abundance .
high stops any other particles being detected
-
vacuum .
Isotopes are atoms of the same element with different mass numbers ,
due to a difference in neutron numbers .
Relative isotopic mass is the mass of one atom of an isotope ,
relative to
% Of the mass of one carbon -
12 .
Relative atomic mass is the weighted average mass of an atom
of an
element ,
relative to of one carbon-12 isotope .
↳ this is calculated
using relative abundances of each isotope .
MASS SPEC
Mass spec allows us to determine relative atomic masses of elements Icom pounds
Vaporise → the sample can
only travel through the machine as a
gas high vacuum
,
.
ionise → allows
sample to be detected
by magnetic field
-
stream of high
energy electrons removes usually one electron
acceleration → in electric field 71000 V. ion interacts with electric field .
deflection → differs based on mass and charge .
•
: more
more
charged deflection
•
in mass : more deflection
lighter
detection → hit ion detector and produce a current .
↳
magnetic field slowly increased to detect higher masses .
•
mass spec gives relative atomic mass of each atom 1molecule detected ,
and its relative abundance .
•
peaks measure m Iz ratio ( assuming 2=2 I
•
molecular ion peak is the highest mlz value ,
not
largest abundance .
high stops any other particles being detected
-
vacuum .
