Chemical equations nuclear equation

In nuclear reactions the total number of nuclear particles, called nucleons (protons plus neutrons), remains the same, but the identities of atoms can change. Just as with chemical equations, nuclear equations reflect the fact that matter is conserved. As a result, the sum of the mass numbers of reacting nuclei must equal the sum of the mass numbers of the product nuclei. There must also be nuclear charge balance—the sum of the atomic numbers of the products must equal the sum of the atomic numbers of the reactants. 

The U-238 atom emits part of its nucleus, two protons and two neutrons, to form a thorium atom. Like chemical equations, nuclear equations must be balanced the numbers of protons and neutrons on both sides of the equation must be equal. This equation is balanced because the sum of the atomic numbers on the right, 90 + 2, is equal to the atomic number on the left, 92. Likewise, the sum of the mass numbers on the right, 234 + 4, equals the mass number on the left, 238. 

The reactions that we discuss in this chapter will be represented by nuclear equations. An equation of this type uses nuclear symbols such as those written above in other respects it resembles an ordinary chemical equation. A nuclear equation must be balanced with respect to nuclear charge (atomic number) and nuclear mass (mass number). To see what that means, consider an equation that we will have a lot more to say about later in this chapter ... 

Actually, then, by our symbol jjU we are representing not an atom, but a nucleus. Our equation is written in terms of nuclei and particles associated with them. This nuclear equation tells us nothing about what compound ol uranium was bombarded with neutrons or what compound of barium is formed. We are summarizing only the nuclear changes. During the nuclear change there is much disruption of other atoms because of the tremendous amounts of energy liberated. We do not know in detail what happens but eventually we return to electrically neutral substances (chemical compounds) and the neutrons are consumed by other nuclei. 

Notice that we do not cancel neutrons, although they appear on both sides of the equation. Like equations for elementary chemical reactions, nuclear equations show the specific process. 

C22-0030. Outline the requirements for a balanced nuclear equation, and explain how they differ from those for a balanced chemical equation. 

A chemical equation describes a chemical reaction in many ways as an empirical formula describes a chemical compound. The equation describes not only which substances react, but the relative number of moles of each undergoing reaction and the relative number of moles of each product formed. Note especially that it is the mole ratios in which the substances react, not how much is present, that the equation describes. In order to show the quantitative relationships, the equation must be balanced. That is, it must have the same number of atoms of each element used up and produced (except for special equations that describe nuclear reactions). The law of conservation of mass is thus obeyed, and also the "law of conservation of atoms. Coefficients are used before the formulas for elements and compounds to tell how many formula units of that substance are involved in the reaction. A coefficient does not imply any chemical bonding between units of the substance it is placed before. The number of atoms involved in each formula unit is multiplied by the coefficient to get the total number of atoms of each element involved. Later, when equations with individual ions are written (Chap. 9), the net charge on each side of the equation, as well as the numbers of atoms of each element, must be the same to have a balanced equation. The absence of a coefficient in a balanced equation implies a coefficient of 1. 

Nuclear chemistry nuclear equations, half-lives, and radioactivity chemical applications... 

Most nuclear reactions involve the breaking apart of the nucleus into two or more different elements or subatomic particles. If we know all but one of the particles, then the unknown particle can be determined by balancing the nuclear equation. When chemical equations are balanced, we add coefficients to ensure that there are the same number of each type of atom on both the left and right of the reaction arrow. However, in order to balance nuclear equations we ensure that there is the same sum of both mass numbers and atomic numbers on the left and right of the reaction arrow. Recall that we can represent a specific isotope of an element by the following symbolization ... 

All the chemical changes and many of the physical changes that we have studied so far involve alterations in the electronic structures of atoms. Electron-transfer reactions, emission and absorption spectra, and X rays result from the movement of electrons from one energy level to another. In all of these, the nuclei of the atoms remain unchanged, and different isotopes of the same element have the same chemical activity. Nuclear chemistry, or radioactivity, differs from other branches of chemistry in that the important changes occur in the nucleus. These nuclear changes also are represented by chemical equations. However, because the isotopes of the same element may, from a nuclear standpoint, be very different in reactivity, it is necessary that the equations show which isotopes are involved. 

Note how the nuclear equation for the radioactive decay of uranium-238 is written. The equation is not balanced in the usual chemical sense because the kinds of nuclei are not the same on both sides of the arrow. Instead, a nuclear equation is balanced when the sums of the nucleons are the same on both sides of the equation and when the sums of the charges on the nuclei and any elementary particles (protons, neutrons, and electrons) are the same on both sides. In the decay of 2 U to give He and 2 oTh, for example, there are 238 nucleons and 92 nuclear charges on both sides of the nuclear equation. 

Nuclear equations, like chemical equations, are a method of keeping track of the involved particles and... 

Just as an ordinary chemical equation is a shortened version of the complete thermochemical equation which expresses both energy and mass balance, each nuclear equation has a term (written or implied) expressing energy balance. The symbol Q is usually used to designate the net energy released when all reactant and product particles of matter are at zero velocity. Q is the energy equivalent of the mass decrease (discussed above) accompanying the reaction. Q is usually expressed in MeV. 

Hiroshima exploded with energy equivalent to about 20,000 tons of TNT.18 But where does all of this energy come from Unlike ordinary chemical reactions, nuclear fission does not involve breaking and forming chemical bonds. Instead, the energy comes from the loss of mass that accompanies the fission reaction. Most, if not all, of the students will be familiar with Einstein s famous equation, E = me2, but few are likely to understand what it means.19 In 1939, Lise Meitner and her nephew Robert Frisch reported their discovery of nuclear fission.20 They realized that the energy that accompanied the fission of uranium nuclei could be accounted for by using Einstein s equation. 

Nuclear transmutations are represented by nuclear equations. Nuclear equations show the change in the nucleus as well as the particle emitted during the decay process. Just like chemical equations, these equations must follow the Law of Conservation of Mass and the Law of Conservation of Charge. That is, they are balanced by equating the sum of mass numbers on both sides of a reaction equation and the sum of atomic numbers on both sides of a reaction equation. 

The theoretical study of any chemical problem which falls within the domain of the Bom-Oppenheimer approximation involves two basic steps (a) the solution of Schrodinger s electronic equation, equation (5), for one or more electronic states over the range of nuclear configurations demanded by the problem and (b) solving the nuclear equations of motion on the potential energy surface, or surfaces, thus obtained. ... 

The AP test requires you to know about nuclear equations, half-lives, radioactivity, and chemical applications of nuclear properties. This chapter begins with a brief review of the history of the nucleus and how we came to know about it and then moves into the required topics. 

Nuclear reaction energies may be included in nuclear equations, just as chemical reaction energies are included in thermochemical equations ... 

Back on Earth, however, chemical reactions are everywhere in our daily lives. We rely on chemical reactions for everything from powering a car to making toast. In this chapter, you will learn how to write balanced chemical equations for these reactions. You will look for patterns and similarities between the chemical equations, and you will classify the reactions they represent. As well, you will learn how to balance and classify equations for nuclear reactions. 

Unlike a chemical equation, the elements are usually different on each side of a balanced nuclear equation. 

The radioactive decay processes you have just read about are all examples of nuclear reactions. As you probably noticed, nuclear reactions are expressed by balanced nuclear equations just as chemical reactions are expressed by balanced chemical equations. However, in balanced chemical equations, numbers and kinds of atoms are conserved in balanced nuclear equations, mass numbers and atomic numbers are conserved. 

In this equation, AT stands for change in energy (joules). Am for change in mass (kg), and c for the speed of light (3.00 X 10 m/s). This equation is of major importance for all chemical and nuclear reactions, as it means a loss or gain in mass accompanies any reaction that produces or consumes energy. 

Describe the differences between a balanced nuclear equation and a balanced chemical equation. (25.2)... 

At first glance, you might mistake this for a chemical equation. The format of the equation is similar to the format of a chemical equation, including elemental symbols and a yields arrow. The elemental notation that is shown for both potassium and calcium is the same as the elemental notation that we covered in Lesson 3-2. However, there is an important difference between this equation and the chemical equations that we have been discussing up until now. Notice that we have different elements on either side of the equation This is evidence that we are looking at a nuclear equation, rather than a chemical one. 

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