Exam Q 7

Question 1

Define mass number

Answer 1

The mass number of an element is the sum of the number of protons and neutrons in the nucleus of an atom of that element

Question 2

Define relative atomic mass (4)

Answer 2

Is defined as:

1. The average of the mass numbers of the isotopes of the element,
2. As they occur naturally.
3. Taking their abundances into account and
4. expressed on a scale in which the atoms of the carbon-12 isotope have a mass of exactly 12 units.

Question 3

What are the two other fundamental processes that occur in mass spectrometry other than detection, acceleration, vaporisation of a substance

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Answer 3

Ionisation and separation

Question 4

List all five processes of mass spectrometry in order

Answer 4

Vaporisation
ionisation
acceleration 
separation 
detection

Question 5

How do you calculate the relative atomic mass of gallium using 60.1% of gallium-69 and 39.9% of gallium-71

Answer 5

work out as 100 atoms first:
60.1 x 69 = 4,146.9
39.9 x 71 = 2832.9 
add together = 6,979.8
average mass of 1 atom (divide by 100) = 69.798