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# Nuclear reaction

## Balancing Nuclear Equations

❶This type of radioactivity results in a decrease in the atomic number by 2 and a decrease in the atomic mass by 4.

## Navigation menu   Eventually, in at Cambridge University, a fully artificial nuclear reaction and nuclear transmutation was achieved by Rutherford's colleagues John Cockcroft and Ernest Walton , who used artificially accelerated protons against lithium-7, to split the nucleus into two alpha particles.

The feat was popularly known as "splitting the atom", although it was not the modern nuclear fission reaction later discovered in heavy elements, in by the German scientists Otto Hahn and Fritz Strassmann. Kinetic energy may be released during the course of a reaction exothermic reaction or kinetic energy may have to be supplied for the reaction to take place endothermic reaction.

This can be calculated by reference to a table of very accurate particle rest masses,  as follows: In a nuclear reaction, the total relativistic energy is conserved. The "missing" rest mass must therefore reappear as kinetic energy released in the reaction; its source is the nuclear binding energy. We first need the energy equivalent of one atomic mass unit:. Hence, the energy released is 0. This is a large amount of energy for a nuclear reaction; the amount is so high because the binding energy per nucleon of the helium-4 nucleus is unusually high, because the He-4 nucleus is " doubly magic ".

The He-4 nucleus is unusually stable and tightly bound for the same reason that the helium atom is inert: Consequently, alpha particles appear frequently on the right hand side of nuclear reactions. This energy is eventually released through nuclear decay. A small amount of energy may also emerge in the form of X-rays. Generally, the product nucleus has a different atomic number, and thus the configuration of its electron shells is wrong. As the electrons rearrange themselves and drop to lower energy levels, internal transition X-rays X-rays with precisely defined emission lines may be emitted.

In writing down the reaction equation, in a way analogous to a chemical equation , one may in addition give the reaction energy on the right side:. The reaction energy the "Q-value" is positive for exothermal reactions and negative for endothermal reactions, opposite to the similar expression in chemistry.

On the one hand, it is the difference between the sums of kinetic energies on the final side and on the initial side. But on the other hand, it is also the difference between the nuclear rest masses on the initial side and on the final side in this way, we have calculated the Q-value above.

If the reaction equation is balanced, that does not mean that the reaction really occurs. The rate at which reactions occur depends on the particle energy, the particle flux and the reaction cross section.

In the initial collision which begins the reaction, the particles must approach closely enough so that the short range strong force can affect them.

As most common nuclear particles are positively charged, this means they must overcome considerable electrostatic repulsion before the reaction can begin. Even if the target nucleus is part of a neutral atom , the other particle must penetrate well beyond the electron cloud and closely approach the nucleus, which is positively charged. Ordinary chemical reactions involve the exchange and sharing of electrons, while nuclear reactions involve alterations in the very core of an atom; that dense nucleus made up of protons and neutrons.

The first concept we discuss is radioactivity. Strictly speaking, radioactivity is the spontaneous disintegration of an unstable atomic nucleus and the subsequent emission of radiation. But what makes atoms radioactive to begin with, and what makes them undergo radioactive decay? It turns out that there is a stable ratio of protons to neutrons for each element; for the first 20 elements on the periodic table hydrogen through calcium , this ratio is 1 proton to 1 neutron, for example.

Protons and neutrons in excess of this stable number can be emitted radioactively. Below we have listed examples of the important types of radioactive decay. Alpha decay occurs when the nucleus emits an alpha particle.

Alpha particles have a positive charge and are equivalent in size to a helium nucleus, and so they are symbolized as. Alpha particles are the largest radioactive particle emitted. This type of radioactivity results in a decrease in the atomic number by 2 and a decrease in the atomic mass by 4.

The equation below shows uranium undergoing alpha decay:. Beta decay occurs when the nucleus emits a beta particle. Beta particles have a negative charge and are much smaller than alpha particles. This type of radioactivity causes an increase in the atomic number by 1 but no change in mass number.

The equation below represents uranium undergoing beta decay. How does a nucleus, which is composed of only protons and neutrons, eject an electron? A neutron is composed of a proton and an electron fused together.

Plutonium can be produced by bombarding uranium with alphaparticles. How many neutrons will be produced as a by-product of eachreaction? Write the nuclear equation for this reaction. When bombarded with a neutron, lithium-6 produces an alpha particle and anisotope of hydrogen.

What isotopeof hydrogen is produced? Neutron bombardment of plutonium yields americium and anotherparticle. Write the nuclear equation and identify the other particle produced. One method of producing plutonium is by bombarding uranium withdeuterium hydrogen-2 , which produces neptunium and 2 neutrons.

Theunstable neptunium then decays to produce plutonium Write the nuclearequations for this two-step reaction. ## Main Topics

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Chemical reactions involve an atom s electrons while nuclear reactions involve the atom s nucleus. Writing a nuclear reaction equation. In order to write an equation for a nuclear reaction, we must first establish some basic rules. Each of the elements involved in the reaction is identified by the chemical symbol.

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Rules for writing nuclear equations 1. the masses on each side of the equation must be equal 2. the charges on each side of the equation must be equal 3. the nuclear charge is the atomic number, and can be used to identify any new elements that form General Format A or a = mass number Z or z = charge; atomic.

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Equations can be written to show how a nucleus changes during a nuclear decay process. With these nuclear equations we track the atomic number and the mass number. For this reason it is important to correctly write the symbols for each particle involved. A nuclear equation is written for an alpha decay and a beta decay below. For this writing nuclear reactions worksheet, high schoolers read about nuclear equations for alpha decay, beta decay and positron emission. They are given the rules for writing nuclear reactions and a sample problem.

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1. Write a nuclear equation for the alpha decay of Pa Pa 91 4He 2 + Ac 89 2. Write a nuclear equation for the beta decay of Fr Fr 87 oe-1 + Ra 88 3. Write a nuclear equation for the alpha and beta decay of Sm Sm 62 4He 2 + oe-1 + Pm 61 4. Write a nuclear equation for the beta decay of Pm Pm . Balancing Nuclear Equations You will need a periodic table in order to complete this activity.