Here's why:

* Atomic Number: The atomic number defines an element. It represents the number of protons in the nucleus of an atom.

* Nitrogen: Nitrogen always has 7 protons.

* Isotopes: Nitrogen-14 is an isotope of nitrogen. Isotopes of an element have the same number of protons but different numbers of neutrons. The number after the element name (in this case, 14) refers to the *mass number*, which is the total number of protons and neutrons.

Therefore, even though nitrogen-14 has a different number of neutrons than other nitrogen isotopes, it still has 7 protons, making its atomic number 7.