The atom number of an element is the same as its.....protons, neutrons, or nucleons?

same at the protons, same as the electrons

Since this is not my area of expertise, I searched Google under the key words "atomic number" to get these possible sources:

http://en.wikipedia.org/wiki/Atomic_number
http://education.jlab.org/glossary/atomicnumber.html
http://www.answers.com/topic/atomic-number

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.

I hope this helps. Thanks for asking.