radioactivity

ra·di·o·ac·tiv·i·ty  (rd--k-tv-t)

n.

1. Spontaneous emission of radiation, either directly from unstable atomic nuclei or as a consequence of a nuclear reaction.

2. The radiation, including alpha particles, nucleons, electrons, and gamma rays, emitted by a radioactive substance.

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radioactivity [ˌreɪdɪəʊækˈtɪvɪtɪ]

n

(Physics / Nuclear Physics) the spontaneous emission of radiation from atomic nuclei. The radiation can consist of alpha, beta, and gamma radiation

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radioactivity  (rd--k-tv-t)

The emission of radiation by unstable atomic nuclei undergoing radioactive decay.

A Closer Look In the nuclei of stable atoms, such as those of lead, the force binding the protons and neutrons to each other individually is great enough to hold together each nucleus as a whole. In other atoms, especially heavy ones such as those of uranium, this energy is insufficient, and the nuclei are unstable. An unstable nucleus spontaneously emits particles and energy in a process known as radioactive decay. The term radioactivity refers to the particles emitted. When enough particles and energy have been emitted to create a new, stable nucleus (often the nucleus of an entirely different element), radioactivity ceases. Uranium 238, a very unstable element, goes through 18 stages of decay before becoming a stable isotope of lead, lead 206. Some of the intermediate stages include the heavier elements thorium, radium, radon, and polonium. All known elements with atomic numbers greater than 83 (bismuth) are radioactive, and many isotopes of elements with lower atomic numbers are also radioactive. When the nuclei of isotopes that are not naturally radioactive are bombarded with high-energy particles, the result is artificial radioisotopes that decay in the same manner as natural isotopes. Each element remains radioactive for a characteristic length of time, ranging from mere microseconds to billions of years. An element's rate of decay is called its half-life. This refers to the average length of time it takes for half of its nuclei to decay.

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radioactivity

the state, property, or process of being radioactive.

See also: Radiation

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The spontaneous emission of radiation, generally alpha or beta particles, often accompanied by gamma rays, from the nuclei of an unstable isotope.

Thesaurus

Noun

1.

radioactivity - the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay radiation corpuscular radiation, particulate radiation - a stream of atomic or subatomic particles that may be charged positively (e.g. alpha particles) or negatively (e.g. beta particles) or not at all (e.g. neutrons) emission - the release of electrons from parent atoms

Translations

radioactivity [ˈreɪdɪəʊækˈtɪvɪtɪ] N → radiactividad f, radioactividad f

radioactivity [ˌreɪdiəʊækˈtɪvɪti] n → radioactivité f
radio alarm n → radio-réveil m
radio alarm clock n → radio-réveil m

radioactivity [ˌreɪdɪəʊækˈtɪvɪtɪ] n → radioattività