Proton Posted on 14th December 201511th May 2021 by ThePD (The Project Definition) A Proton (p or p+) is 1) a component of an atomic nucleus with a mass defined as 1; 2) a very small particle of matter. Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window) Related Posted in Science and tagged chemistry, physics. ThePD (The Project Definition) ThePD has been developing the Preferred Project Definitions based on the actual project execution and operation experiences and knowledge with the Project Language, and sharing with you daily basis.