Separate Mass Number from Atomic Number - Practice 2

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Mass number is the number of protons plus neutrons in a particular nucleus. Subtract atomic number, the proton count, to find neutrons. Mass number is an integer count, not the average atomic mass printed on many periodic tables.

Worked example

A nucleus with mass number 23 and atomic number 11 has 23 - 11 = 12 neutrons.

A nucleus count model labels 6 protons P and 7 neutrons N. Atomic number is 6; mass number is 13. Electrons are omitted and the layout is not a physical scale model.

Question 1 A model isotope has atomic number 10 and mass number 22. How many neutrons are in its nucleus? Answer

Question 2 A model isotope has atomic number 11 and mass number 24. How many neutrons are in its nucleus? Answer

Question 3 A model isotope has atomic number 12 and mass number 26. How many neutrons are in its nucleus? Answer

Question 4 A model isotope has atomic number 13 and mass number 28. How many neutrons are in its nucleus? Answer

Question 5 A model isotope has atomic number 14 and mass number 30. How many neutrons are in its nucleus? Answer