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Edexcel IGCSE Physics 7.3 Atomic number, mass number & isotopes

Practise using atomic number, mass number and isotope notation to identify protons, neutrons and nuclei in Edexcel IGCSE Physics questions.

Syllabus
First assessment 2019
Course
Physics 4PH1

Exam points

  • calculate neutrons from mass number minus atomic number in isotope symbols
  • distinguish isotopes by same proton number and different neutron number in written definitions
  • interpret numbers beside nuclide symbols as proton number and nucleon number for a nucleus

7.3 Atomic number, mass number and isotopes question 1

[Maximum number: 1]

This question is about radioactive isotopes used for medical imaging.

lodine-131 is represented by this symbol.

53131I{ }_{53}^{131} \mathrm{I}

How many neutrons are in the nucleus of an atom of iodine-131?

A

53

B

78

C

131

D

184

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