The atomic number of nitrogen is 7. How many protons, neutrons, and electrons make up an atom of nitrogen-15?

1 Answer
anor277
Nov 26, 2015

By definition, if #Z#, the atomic number #=# #7#, then there are 7 protons, 7 electrons, and 8 neutrons!

Explanation:

The atomic number is by definition the number of protons, positively charged particles, contained within the atomic nucleus. So if there are 7 protons, there MUST be 7 electrons, 7 negatively charged particles. Why? Because matter is electrically neutral, and positive and negative particles must be equal.

Electrons have negligible mass; the mass number depends on the number of protons contained within the nucleus, PLUS the number of neutrons. Given that we have #""^15N#, there must be 8 neutrons contained within the nucleus. Capisce?

Related questions
See all questions in Isotope Notation
Impact of this question
50877 views around the world
You can reuse this answer
Creative Commons License