Unit 7 Lesson 4: Modeling Nuclear Processes

a nuclear process in which small nuclei join to form a larger nucleus

the small, dense, positively-charged center of an atom

a positively-charged particle that makes up the positive charge in the nucleus of an atom

You get a model of nuclear fusion. Nuclear fusion is a nuclear process in which small nuclei join to form a larger nucleus.

. When two small nuclei fuse, the nucleus that forms has a greater number of protons than either of the small starting nuclei

This model shows that the total mass number and the total charge do not change during nuclear fusion. The sum of the mass numbers of the hydrogen nuclei equals the mass number of the helium nucleus. Likewise, the sum of the atomic numbers of the hydrogen nuclei equals the atomic number of the helium nucleus. Although the mass number remains the same during nuclear fusion, the total mass present decreases. The decrease in mass is directly related to the energy that is released during nuclear processes. A small amount of mass is converted into a large amount of energy. The amount of energy released is calculated according to Einstein’s famous equation E=mc2 , where m is the mass converted and c is the speed of light. Thus, even an extremely small amount of mass can produce a large amount of energy.

The number of protons in a starting nucleus is less than the number of protons in the nucleus produced. The nucleus produced is formed from two smaller nuclei, so the resulting nucleus contains the protons contained in both initial nuclei. The nucleus produced must contain more protons than either of the initial nuclei.

I would divide the magnets into two groups. I would then push them toward one another until the attraction pulled them together into one large group.

The equation does not model nuclear fusion. In this equation, a single large nucleus separates into two smaller nuclei, which is the opposite process of nuclear fusion.

During nuclear fusion, two small nuclei join together to form a larger nucleus.

The amount of energy released by the sun is very large and would require a huge amount of fuel to maintain a combustion reaction for billions of years. Combustion also requires the presence of oxygen. The direct conversion of matter into energy in nuclear processes is more reasonable for the quantity of energy, the length of time the reaction has been happening, and the materials that are known to make up the sun.

The model in the video does not show any neutrons. Without neutrons, the forces between the positive charges of the protons would strongly repel each other. This repulsion would make the nucleus unstable and would force the protons apart.

The number of protons in a nucleus before fusion is less than the number of protons in the nucleus after fusion occurs. The nucleus produced is formed from two smaller nuclei, so the resulting nucleus contains the protons contained in both initial nuclei. The nucleus produced must contain more protons than either of the initial nuclei.

A nucleus of nitrogen will form. Boron has 5 protons, and helium has 2 protons. The resulting nucleus should have 7 protons, which is the atomic number of nitrogen.

A model of the reaction would show the helium nucleus combining with the lithium nucleus. The resulting nucleus contains three protons from the lithium nucleus and two protons from helium. After the hydrogen atom is emitted, one proton would be present in the hydrogen nucleus that forms. The other nucleus produced would have four protons and be a nucleus of beryllium.

Because every nucleus is positively charged, as two nuclei approach each other they repel, or push away from each other. The force pushing them apart increases the closer they get. For fusion to occur, the fusing particles must have enough energy to overcome the repulsive forces between them. This energy is provided by extremely high temperatures within the fusion reactor. The reaction most likely to be used in a nuclear fusion reactor to generate electrical energy takes place at about 150 million degrees Celsius. This reaction is shown by the following model.

Because nuclei fuse to form a larger nucleus, the large nucleus that forms has more protons in it than either of the starting nuclei has.

Binding energy indicates how stable a nucleus is. The greater the binding energy, the more stable the nucleus.

To make comparisons of the stability of nuclei easier, the binding energy is divided by the total number of nucleons (protons and neutrons) in the nucleus.

Binding energy is the amount of energy needed to disassemble a nucleus. This same amount of energy would be released if the nucleus were constructed from its separate particles.

iron

. Thus, nuclear fusion reactions that produce nuclei of atoms up to iron can release energy.

The release of energy during nuclear fusion is a result of the difference in the binding energy of the products compared with that of the reactants. The more massive the nucleus that forms, the greater its binding energy per nucleon.

The deuterium-tritium reaction occurs at a low temperature compared with other fusion reactions, which will help to reduce the energy cost to run the reactor. Because the starting materials are forms of hydrogen, there are abundant supplies of them that could be collected from water.