noun
proton
PROH-ton
noun
1
A positively charged particle found in the nucleus of every atom.
"The number of protons in an atom determines which element it is."
"Protons and neutrons together make up most of an atom's mass."
How to Use Proton
Learner’s notesIn plain EnglishA tiny positively-charged particle inside an atom's nucleus, alongside neutrons.
Common pairings
proton beam
proton number
Word Forms
protons plural
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The number of _____ in an atom determines which element it is.
Etymology
Coined in 1920 by physicist Ernest Rutherford from Greek prôton, "first thing," echoing the earlier-named electron.