: an elementary particle that is identical with the nucleus of the hydrogen atom, that along with the neutron is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron, and that has a mass of 1.673 × 10−27 kilogram
Examples of proton in a Sentence
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The reaction between deuterium and helium-3 would expel protons, and their positive charge would be harnessed for propulsion, as well as power to run a spacecraft’s systems.
—
Margherita Bassi, Smithsonian Magazine, 18 Apr. 2025
In its lowest-energy state, the proton and electron will have spins oriented in opposite directions.
—ArsTechnica, 16 Apr. 2025
In this process, subatomic particles such as protons and neutrons—and even entire atomic nuclei—could be smashed together, fusing to form heavier nuclei and releasing an enormous amount of energy.
—Phil Plait, Scientific American, 10 Apr. 2025
At this hot cocoon, the researchers suggest the jet's high-energy photons can interact with atomic nuclei, transmuting protons to neutrons incredibly quickly — on the order of a nanosecond.
—Charles Q. Choi, Space.com, 7 Apr. 2025
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Margherita Bassi, Smithsonian Magazine, 18 Apr. 2025
In its lowest-energy state, the proton and electron will have spins oriented in opposite directions.
—ArsTechnica, 16 Apr. 2025
In this process, subatomic particles such as protons and neutrons—and even entire atomic nuclei—could be smashed together, fusing to form heavier nuclei and releasing an enormous amount of energy.
—Phil Plait, Scientific American, 10 Apr. 2025
At this hot cocoon, the researchers suggest the jet's high-energy photons can interact with atomic nuclei, transmuting protons to neutrons incredibly quickly — on the order of a nanosecond.
—Charles Q. Choi, Space.com, 7 Apr. 2025
See All Example Sentences for proton
Cite this Entry
“Proton.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/proton. Accessed 30 Apr. 2025.
Copy CitationKids Definition
proton
noun
pro·ton
ˈprō-ˌtän 
: an atomic particle that occurs in the nucleus of every atom and carries a positive charge equal in size to the negative charge of an electron
Medical Definition
proton
noun
pro·ton
ˈprō-ˌtän
: an elementary particle that is identical with the nucleus of the hydrogen atom, that along with neutrons is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron, and that has a mass of 1.673×10−24 gram
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