Which radioisotope is matched with its decay mode

The spontaneous change of an unstable nuclide into another is radioactive decay. The unstable nuclide is called the parent nuclide ; the nuclide that results from the decay is known as the daughter nuclide. The daughter nuclide may be stable, or it may decay itself. The radiation produced during radioactive decay is such that the daughter nuclide lies closer to the band of stability than the parent nuclide, so the location of a nuclide relative to the band of stability can serve as a guide to the kind of decay it will undergo Figure 3.

Figure 3. The alpha particle removes two protons green and two neutrons gray from the uranium nucleus. An alpha particle is composed of two protons and two neutrons and is the same as a helium nucleus. We often use 2 4 He to represent an alpha particle. We can represent the emission of an alpha particle with a chemical equation—for example, the alpha-particle emission of uranium is as follows:. Rather than calling this equation a chemical equation, we call it a nuclear equation to emphasize that the change occurs in an atomic nucleus.

How do we know that a product of this reaction is 90 Th? We use the law of conservation of matter , which says that matter cannot be created or destroyed. This means we must have the same number of protons and neutrons on both sides of the nuclear equation. If our uranium nucleus loses 2 protons, there are 90 protons remaining, identifying the element as thorium. Moreover, if we lose four nuclear particles of the original , there are remaining.

Thus we use subtraction to identify the isotope of the Th atom—in this case, 90 Th. A beta particle is an electron ejected from the nucleus not from the shells of electrons about the nucleus and has a -1 charge. We can also represent a beta particle as -1 0 e. The net effect of beta particle emission on a nucleus is that a neutron is converted to a proton. The overall mass number stays the same, but because the number of protons increases by one, the atomic number goes up by one.

Carbon decays by emitting a beta particle:. Again, the sum of the atomic numbers is the same on both sides of the equation, as is the sum of the mass numbers. Electromagnetic radiation can be characterized into different categories based on the wavelength and photon energies. The electromagnetic spectrum shown in figure 3.

Note that the human sensory adaptations of sight and hearing have evolved to detect electromagnetic radiation, with radio waves having wavelengths between 1 mm and km and visible light having wavelengths between — nm. Technological advances have helped humankind utilize other forms of electromagnetic radiation including X-rays and microwaves.

A diagram of the electromagnetic spectrum, showing various properties across the range of frequencies and wavelengths. Image Available from Wikipedia. Some electromagnetic radiation with very short wavelengths are active enough that they may knock out electrons out of atoms in a sample of matter and make it electrically charged.

The types of radiation that can do this are termed ionizing radiation. X-rays and Gamma rays are examples of ionizing radiation. Some radioactive materials, emit gamma radiation during their decay. For example, in the decay of radioactive technetium, a gamma ray is emitted. Note that in radioactive decay where the emission of gamma radiation occurs, that the identity of the parent material does not change, as no particles are physically emitted.

Sometimes the radioactive decay of a sample can result in the release of multiple forms of radioactivity. For example, in the radioactive decay of radon, both alpha and gamma radiation are emitted, with the latter having an energy of 8. This may not seem like much energy, but if 1 mol of Rn atoms were to decay, the gamma ray energy would be 4. Alpha, beta, and gamma emissions have different abilities to penetrate matter. The relatively large alpha particle is easily stopped by matter although it may impart a significant amount of energy to the matter it contacts.

Beta particles penetrate slightly into matter, perhaps a few centimeters at most. Gamma rays can penetrate deeply into matter and can impart a large amount of energy into the surrounding matter. Table 3. Figure provided by Stannered. In addition to the three major types of radioactive particles listed above, two additional less common types of emissions have been discovered.

These include positron emission and electron capture. Oxygen is an example of a nuclide that undergoes positron emission:. Positron emission is observed for nuclides in which the n:p ratio is low. These nuclides lie below the band of stability. Positron decay is the conversion of a proton into a neutron with the emission of a positron.

The n:p ratio increases, and the daughter nuclide lies closer to the band of stability than did the parent nuclide. The positron has the mass of an electron, but a positive charge. For example, potassium undergoes electron capture:. Electron capture occurs when an inner shell electron combines with a proton and is converted into a neutron. The loss of an inner shell electron leaves a vacancy that will be filled by one of the outer electrons. As the outer electron drops into the vacancy, it will emit energy.

In most cases, the energy emitted will be in the form of an X-ray. Electron capture has the same effect on the nucleus as does positron emission: The atomic number is decreased by one and the mass number does not change. This increases the n:p ratio, and the daughter nuclide lies closer to the band of stability than did the parent nuclide.

Whether electron capture or positron emission occurs is difficult to predict. The choice is primarily due to kinetic factors, with the one requiring the smaller activation energy being the one more likely to occur. Summary of the type, nuclear equation, representation, and any changes in the mass or atomic numbers for various types of decay. Occasionally, an atomic nucleus breaks apart into smaller pieces in a radioactive process called spontaneous fission or fission.

Typically, the daughter isotopes produced by fission are a varied mix of products, rather than a specific isotope as with alpha and beta particle emission. Often, fission produces excess neutrons that will sometimes be captured by other nuclei, possibly inducing additional radioactive events.

Uranium undergoes spontaneous fission to a small extent. One typical reaction is. As with any nuclear process, the sums of the atomic numbers and mass numbers must be the same on both sides of the equation. Spontaneous fission is found only in large nuclei. The smallest nucleus that exhibits spontaneous fission is lead Fission is the radioactive process used in nuclear power plants and one type of nuclear bomb.

For example, cobalt, an isotope that emits gamma rays used to treat cancer, has a half-life of 5. In a given cobalt source, since half of the nuclei decay every 5. Note that for a given substance, the intensity of radiation that it produces is directly proportional to the rate of decay of the substance and the amount of the substance.

Thus, a cobalt source that is used for cancer treatment must be replaced regularly to continue to be effective. The Decay of Cobalt For cobalt, which has a half-life of 5. Note that every half-life is the same length of time.

Since every half-life for a radionuclide is the same length of time, we can use the following equation to calculate how much radioactive nuclide is remaining after the passage of any number n of half-lives:. Question: The half-life of Zn is 2.

If one had Step 1. Step 2. Use the Isotope Remaining equation to solve for how much isotope will remain after the number of half-lives determined in step 1 have passed. Damaging Effects of Ionizing Radiation.

Lower frequency, lower-energy electromagnetic radiation is nonionizing, and higher frequency, higher-energy electromagnetic radiation is ionizing.

Energy absorbed from nonionizing radiation speeds up the movement of atoms and molecules, which is equivalent to heating the sample. Which sample of ethanol has particles with the highest average kinetic energy?

The molarity of an aqueous solution of NaCl is defined as the. A real gas behaves least like an ideal gas under the conditions of. Which sample of matter can be separated into different substances by physical means? At STP, 1. Which statement describes the particles of an ideal gas? The particles move in well-defined, circular paths.

When the particles collide, energy is lost. There are forces of attraction between the particles. The volume of the particles is negligible. A chemical reaction between iron atoms and oxygen molecules can only occur if. Which statement describes this equilibrium? The H 2 O s melts faster than the H 2 O l freezes. The H 2 O l freezes faster than the H 2 O s melts.

The mass of H 2 O s must equal the mass of H 2 O l. The mass of H 2 O l and the mass of H 2 O s each remain constant. A molecule of an organic compound contains at least one atom of. In a chemical reaction, the difference between the potential energy of the products and the potential energy of the reactants is equal to the. A carbon-carbon triple bond is found in a molecule of. Which statement describes one characteristic of an operating electrolytic cell?

It produces electrical energy. It requires an external energy source. It uses radioactive nuclides. It undergoes a spontaneous redox reaction. Which compound when dissolved in water is an Arrhenius acid? CH 3 OH. An acid can be defined as an. OH - acceptor. OH - donor. Which nuclear emission has no charge and no mass? During which process can Which radioisotope is matched with its decay mode? Which reaction is accompanied by the release of the greatest amount of energy? Which two atoms are isotopes of the same element?

Which Lewis electron-dot diagram represents an atom in the ground state for a Group 13 element? Which element forms a compound with chlorine with the general formula MCl? A sample of an element has a mass of To which number of significant figures should the calculated density of the sample be expressed? Which characteristics both generally decrease when the elements in Period 3 on the Periodic Table are considered in order from left to right?

Which formula is both a molecular and an empirical formula? An atom of argon in the ground state tends not to bond with an atom of a different element because the argon atom has. Which formula represents a molecule having a nonpolar covalent bond? Which compound has the lowest vapor pressure at 50 degrees C?

Given the potential energy diagram and equation representing the reaction between substances A and D:. A sample of gas confined in a cylinder with a movable piston is kept at constant pressure.

The volume of the gas doubles when the temperature of the gas is changed from. According to Table F, which compound is soluble in water? Which changes occur when the temperature of this system is decreased?