alpha particle

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noun Physics.

a positively charged particle consisting of two protons and two neutrons, emitted in radioactive decay or nuclear fission; the nucleus of a helium atom.

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Origin of alpha particle

First recorded in 1900–05

Words nearby alpha particle

alpha-ketoglutaric acid, alpha-linolenic acid, alpha male, alpha-naphthylthiourea, alphanumeric, alpha particle, alpha privative, alpha radiation, alpha ray, alpha receptor, alpha rhythm

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use alpha particle in a sentence

Some particles — including protons, neutrons, alpha particles and beta particles — travel through space at high speeds.
Scientists Say: Radiation|Bethany Brookshire|March 29, 2021|Science News For Students
Mercury 203 plus an alpha particle gives nice, stable Lead 207.
The Bramble Bush|Gordon Randall Garrett
An alpha particle is the nucleus of a helium atom and is made up of two protons and two neutrons; it carries two positive charges.
LRL Accelerators|Lawrence Radiation Laboratory
There can thus be no doubt that the alpha particle becomes a helium atom when its positive charge is neutralized.
A Brief Account of Radio-activity|Francis Preston Venable

This stopping power of an atom for an alpha particle is approximately proportional to the square root of its atomic weight.
A Brief Account of Radio-activity|Francis Preston Venable
Ionium expels an alpha particle and becomes radium, which is a bivalent element resembling barium belonging to the second group.
A Brief Account of Radio-activity|Francis Preston Venable

British Dictionary definitions for alpha particle

alpha particle

noun

a helium-4 nucleus, containing two neutrons and two protons, emitted during some radioactive transformations

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for alpha particle

alpha particle

A positively charged particle that consists of two protons and two neutrons bound together. It is emitted by an atomic nucleus undergoing radioactive decay and is identical to the nucleus of a helium atom. Because of their relatively large mass, alpha particles are the slowest and least penetrating forms of nuclear radiation. They can be stopped by a piece of paper. See more at radioactive decay.