2.2 relative mass

Question 1

define relative isotopic mass

Answer 1

is the mass of an isotope relative to 1/12th of the mass of carbon -12

Question 2

define relative atomic mass and its other notaions

Answer 2

Ar: is the weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12

Question 3

how do we determin the relative atomic mass

Answer 3

useing a mass spectrometer the vaporised ions are accelerated and heavier ones are harder to deflect so the individual ions are seperated and detectedand recorderd as a mass-to-charge ratio m/z relative mass of ion/relative charge on ion.

Question 4

relative atomic mass formula

Answer 4

ram=(%xmass)+(%xmass)/100

Question 5

how do we determine the relative isotopic mass

Answer 5

can record m/z ratio accuratley using a mass spectrometer for each isotope so accurate relative isotopic masses can be measured.

Question 6

Do isotopes react differently?

Answer 6

Different ispotopes have the same number of electrons the number of neutrons has no effect on an element therefore react the same way.

Question 7

Do isotopes have different physical properties?

Answer 7

Minor differnece in physical properties can occur becuase with a higher mass isotope an element can have a higher BP and density eg heavy water

Question 8

What is meant by ‘the weighted mean’

Answer 8

takes into account
1. % abundance of each isotope
2. the relative isotopic mass of each isotope

Question 9

when do you need to use term: relative formula mass

Answer 9

For compounds with giant structures,

Question 10

when do you need to use term: relative molecular mass

Answer 10

For simple molecules

Question 11

Whats the purposes of mass spectrometry

Answer 11

1. determine the relative isotopic masses and abundances of the isotope

Question 12

what does m/z stand for

Answer 12

M stands for mass
Z stands for charge of ion