Nuclear fusion
nuclear fusionThe joining together of two smaller atomic nuclei to produce a larger nucleus. Radiation is released when this happens. Nuclear fusion happens in stars like our Sun, and in hydrogen bombs. is when two small, light nucleiNuclei is the plural of nucleus. The nucleus is the central part of an atom. It contains protons and neutrons, and has most of the mass of the atom. join together to make one heavy nucleus. Fusion reactions occur in stars where two hydrogen nuclei fuse together under high temperatures and pressure to form a nucleus of a helium isotopeAtoms of an element with the same number of protons and electrons but different numbers of neutrons..
There are a number of different nuclear fusion reactions happening in the Sun. The simplest is when four hydrogen nuclei become one helium nuclei.
\(4_{1}^{1} H \rightarrow _{2}^{4}He\)
The combined mass of four hydrogen nuclei is 6.693 脳 10-27 kilograms (kg). The mass of one helium nucleus is 6.645 脳 10-27 kg. This means that there is a missing amount of mass equalling 0.048 脳 10-27 kg.
The missing mass is converted to energy, which radiatesSpreads out from a source. Energy is transferred聽as a wave. away. This is seen happening in the Sun. In all nuclear reactionChanges that occur in the nucleus of an atom. Eg due to radioactive decay, nuclear fission or nuclear fusion. a small amount of the mass changes to energy.
However, the issue with fusion is that it requires the fusing of nuclei, which are positive particles. As two nuclei approach each other, they will repelObjects that tend to push apart because of a force between them repel each other. because they have the same chargeProperty of matter that causes a force when near another charge. Charge comes in two forms, positive and negative. For example, a negative charge causes a repulsive force on a neighbouring negative charge.. The fusion of the nuclei has to happen quickly so that the repulsion of the charges does not have time to stop it from happening.
A way that particles can travel that quickly is by being in a hot gas or in plasmaA state of matter achieved by heating a gas to the point where electrons gain enough energy to leave their electron orbits., like in the Sun.