The atomic number of nitrogen is 7. Which of the following explains the greater mass number of nitrogen-15 compared to nitrogen-14? Nitrogen-15 contains ________.
A) 7 neutrons and nitrogen-14 contains 8 neutrons
B) 8 neutrons and nitrogen-14 contains 7 neutrons
C) 8 protons and nitrogen 14 contains 7 protons
D) 15 protons and nitrogen-14 contains 14 protons

Question

Quizplus · Accepted Answer

The mass number of an isotope is the sum of its protons and neutrons. Since nitrogen's atomic number is 7 (indicating 7 protons), the difference in mass number between nitrogen-15 and nitrogen-14 must be due to the difference in the number of neutrons. Nitrogen-15 has 8 neutrons (15 - 7 = 8) and nitrogen-14 has 7 neutrons (14 - 7 = 7).

The Atomic Number of Nitrogen Is 7