Atoms beta emission

WEB Strontium-90 is a dangerous byproduct of atomic testing because it mimics the action of calcium in the body. It decays in two beta emissions to give zirconium-90 (Nudear mass = 89.8824 g). 

Problem 1.14 Half-life of radioactive element is 2800 years. How many atoms of the element are required to produce an average of 10 beta emissions per hour ... 

Know that nuclear stability is best related to the neutron-to-proton ratio (n/p), which starts at about 1/1 for light isotopes and ends at about 1.5/1 for heavier isotopes with atomic numbers up to 83- All isotopes of atomic number greater than 84 are unstable and will commonly undergo alpha decay. Below atomic number 84, neutron-poor isotopes will probably undergo positron emission or electron capture, while neutron-rich isotopes will probably undergo beta emission. 

Uranium is the fourth metal in the actinide series. It looks much like other actinide metallic elements with a silvery luster. It is comparatively heavy, yet malleable and ductile. It reacts with air to form an oxide of uranium. It is one of the few naturally radioactive elements that is fissionable, meaning that as it absorbs more neutrons, it splits into a series of other lighter elements (lower atomic weights) through a process of alpha decay and beta emission that is known as the uranium decay series, as follows U-238—> Th-234—>Pa-234—>U-234—> Th-230 Ra-226 Rn-222 Po-218 Pb-2l4 At-218 Bi-2l4 Rn-218 Po-2l4 Ti-210—>Pb-210—>Bi-210 Ti-206—>Pb-206 (stable isotope of lead,... 

A hydrogen isotope with a nucleus consisting of one proton and two neutrons (the nucleus is referred to as the triton). Tritium, a radioisotope symbolized by iH or T, decays by negative beta emission (0.01860 MeV) with a half-life of 12.32 years. The atomic weight of tritium is 3.01605 amu. It is frequently used in metabolic and kinetic experiments. The following decay data indicate the time followed by the fraction of original amount at the specified time 0, 1.000 1 month, 0.995 2, 0.991 3,... 

Symbol Lu atomic number 71 atomic weight 174.97 a lanthanide series element an /-block inner-transition metal electron configuration [Xe]4/i45di6s2 valence -1-3 atomic radius (coordination number 12) 1.7349A ionic radius (Lu3+) 0.85A two naturally-occurring isotopes Lu-176 (97.1%) and Lu-175(2.59%) Lu-172 is radioactive with a half-life of 4xl0i° years (beta-emission) several artificial isotopes known, that have mass numbers 155, 156, 167—174, 177—180. 

Three main forms of radioactive decay involve the emission of alpha particles, beta particles, and gamma rays. An alpha particle is equivalent to the nucleus of a helium atom. Beta particles are nothing more than electrons. Gamma rays are a form of electromagnetic radiation. 

Thorium-234 is also radioactive. When it decays, it emits a beta particle. Recall that a beta particle is an electron emitted by a neutron as the neutron transforms to a proton. So with thorium, which has 90 protons, beta emission leaves the nucleus with one fewer neutron and one more proton. The new nucleus has 91 protons and is no longer thorium now it is the element protactinium. Although the atomic number has increased by 1 in this process, the mass number (protons + neutrons) remains the same. The nuclear equation is... 

An atomic battery for pocket watches has been developed which uses the beta particles from 147Pm as the primary energy source. The half-life of147Pm is 2.62 years. How long would it take for the rate of beta emission in the battery to be reduced to 10% of its initial value ... 

C. All four choices are balanced mathematically. "A" leaves scandium-41 as a decay product, not scandium-45. "B" and "D" require the addition of particles not normally present in the atom. If these reactions do occur, they are not decay reactions because they are not spontaneous. "C" involves the common decay mechanism of beta emission. 

There are five main types of emissions alpha emission, beta emission, positron emission, electron capture, and gamma emission. Four of these produce changes in the elements undergoing decay, and the end result is a more stable atomic structure. 

Although there are two types of (3-particles ((3 and (3 ), the former is usually referred to as a positron, so we ll refer to only the (3 particle as a beta particle. In a beta emission, a beta particle is ejected from the atom. A beta particle has all of the properties of an electron (virtually massless, negative charge), yet it is created by the conversion of a neutron in the nucleus to a proton and an electron (beta particle). The proton remains in the nucleus, and the beta particle is ejected from the nucleus. An example of a beta emission is ... 

Q Atoms whose nuclei are above the band of stability (high neutron-to-proton ratio) can lower their numbers of neutrons by undergoing beta emissions. The typical pattern for these is that the mass number (number of neutrons + number of protons) is greater than the atomic weight. Remember that beta emissions convert neutrons into protons and beta particles. 

This process has been used to produce countless isotopes, including many radioactive isotopes. In addition, it has allowed scientists to produce elements with atomic numbers that are higher than that of the largest naturally occurring element, uranium. These elements are known as transuranium elements. In 1940, E. M. McMillan and P. H. Abelson of the University of California, Berkeley produced the first transuranium element, neptunium (Np, Z=93), by bombarding uranium-238 with neutrons. The nuclei that captured the neutrons were converted to uranium-239, which decayed into neptunium-239 during a beta emission. The reaction is shown below ... 

The correct answer is (A). Beta emissions are the result of a neutron converting to a proton and an electron. The formation of the proton causes an increase in atomic number, but the mass number remains unchanged. 

In spite of all the new approaches which illuminated the outer regions of the atom, the center or nucleus of the atom continued to remain a bundle of uncertainties. Something of the composition of the nuclei of a few elements was already known. This information came from a study of the spontaneous disintegration of radium and other radioactive elements, such as thorium, polonium, uranium, and radon. These elements break down of their own accord into simpler elements. Soon after the Curies discovery of radium, Rutherford and Frederick Soddy, his student and collaborator, had found that the spontaneous breaking down of radium resulted in the emission of three types of rays and particles. Radium ejected alpha particles (ionized helium atoms), beta particles (electrons), and gamma rays (similar to X-rays). In radioactive elements, at least, it was believed that the nucleus contained electrons, protons, and electrified helium particles. 

Note that the atomic number of the product nucleus, has increased by one. The nitrogen-14 atom now has a stable neutron-to-proton ratio of 1 1. Thus, beta emission has the effect of increasing the stability of a neutron-rich atom by lowering its neutron-to-proton ratio. The resulting atom is closer to, if not within, the band of stability. 

A direct comparison of atomic masses (Table 19.1) lets us determine whether beta emission can take place. 

The radioactive nuclide 29CU decays by beta emission to loZn or by positron emission to fsNi- The maximum kinetic energy of the beta particles is 0.58 MeV, and that of the positrons is 0.65 MeV. The mass of the neutral Cu atom is 63.92976 u. 

A puzzling observation that led to the discovery of isotopes was the fact that lead obtained from uranium-containing ores had an atomic mass lower by two full atomic mass units than lead obtained from thorium-containing ores. Explain this result, using the fact that decay of radioactive uranium and thorium to stable lead occurs via alpha and beta emission. 

Thus, beta emission results in an increase of one in the number of protons (the atomic number) and a decrease of one in the number of neutrons, with no change in mass number. Examples of beta particle emission are... 

Strontium-90 is one of the harmful radionuclides that results from nuclear fission explosions. It decays by beta emission with a half-fife of 28 years. How long would it take for 99.99% of a given sample released in an atmospheric test of an atomic bomb to disintegrate ... 

Some radioactive nuclides have a neutron-to-proton ratio that is too high, placing them above the band of stability. To reach a more stable state they undergo beta emission ( 3 ). In this process, a neutron becomes a proton and an electron. The proton stays in the nucleus, and the electron, which is called a beta particle in this context, is ejected from the atom. 

Note that in beta emission, the radioactive nuclide changes into a different element with an atomic number that is higher by 1 but the same mass number. 

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