Fields, Thomas H. Physics Division, Argonne National Laboratory, Argonne, Illinois.
Last reviewed:March 2019
Show previous versions
- Proton, published November 2017:Download PDF Get Adobe Acrobat Reader
- Proton, published June 2014:Download PDF Get Adobe Acrobat Reader
- Intrinsic properties
- Search for decay
- Related Primary Literature
- Additional Reading
A positively charged composite particle found in the nucleus of every chemical element. Protons are subatomic particles composed of three elementary particles known as quarks, specifically two "up" quarks and one "down" quark (Fig. 1). The sum of the fractional charges of the quarks gives the proton a positive electric charge of one. Being made of three quarks, protons are categorized as baryons. Baryons belong to a broader particle family called hadrons which participate in all four fundamental interactions, or forces of nature: electromagnetism, the strong nuclear interaction, the weak nuclear interaction, and gravity. Protons are the lightest baryon in terms of mass and the only stable baryon known in the universe. Along with the second-lightest baryon, the neutrally charged neutron, protons comprise the nuclei of atoms. Each element in the periodic table is defined and distinguished by the unique number of protons in its nucleus, called the atomic number. An atom’s atomic number largely determines its chemical properties. See also: Atomic nucleus; Atomic number; Baryon; Chemistry; Electric charge; Electromagnetism; Elementary particle; Fundamental interactions; Gravity; Hadron; Periodic table; Quark
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 45 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information