To find the number of neutrons in a sulfur atom, you need to know:

* Atomic Number: This tells you the number of protons in the atom. Sulfur's atomic number is 16.

* Atomic Mass: This is the average mass of the atom, which is primarily determined by the number of protons and neutrons. Sulfur's atomic mass is approximately 32.

Here's how to calculate the number of neutrons:

1. Neutrons = Atomic Mass - Atomic Number

2. Neutrons = 32 - 16 = 16

Therefore, a sulfur atom has 16 neutrons.