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Nuclear Chemistry. The Nucleus. Inside the nucleus there are: Protons Neutrons The nucleus is held together by the strong nucleus force. . The Nucleus. The nucleus is not always stable! The number of protons and neutrons can influence the stability of the nucleus.
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The Nucleus • Inside the nucleus there are: • Protons • Neutrons • The nucleus is held together by the strong nucleus force.
The Nucleus • The nucleus is not always stable! • The number of protons and neutrons can influence the stability of the nucleus. • Usually a 1:1 ratio is stable. • More than this is unstable • Certain isotopes of elements are said to be unstable, and as a result they break down radioactive. • All elements with an atomic number above 82 have at least one radioactive isotope.
Radioactivity • There are three major types of radioactivity: • Composed of 2 protons and 2 neutrons • A helium nucleus • Made of a single negative charge • Basically an electron • High energy photon • No mass
Types of Radioactivity • Alpha particles lost: • A nucleus loses 2 protons and 2 electrons • This produces a loose alpha particle and an atom that is “lighter” with an atomic number lower by two and an atomic mass lower by 4 amus.
Types of Radioactivity • Beta particles lost: • A neutron is made up smaller particles • In radioactive isotopes sometimes a neutron will spontaneously break apart, releasing a beta particle (electron). • What remains is a proton • The neutron breaks apart into a proton and an electron. • The electron is released from the nucleus and the proton stays.
Types of Radioactivity • Gamma Rays: • The most penetrating and high energy type of radioactivity. • Large amounts of photon energy is released • The nucleus is unchanged in numbers of protons and neutrons, but becomes more stable.
Strength of Radioactivity • Alpha particles are the most heavy but least penetrating. • Gamma rays are pure energy, have no mass, but are the most penetrating.
Nuclear Reactions • 1. Fission: This occurs when a radioactive nucleus splits to form two smaller, more stable nuclei • This can lead to dangerous chain reactions!
1. Fission: Nuclear Reactors and Bombs • A common source of Uranium-235 is used as a fuel in nuclear reactions. • It undergoes a number of reactions to release a great deal of energy, which in a reactor is harvested and used for power.
1. Fission: Nuclear Reactors and Bombs • Another common source of fuel is Uranium-238 • The end result of all of the reactions is a stable isotope of lead!
Nuclear Reactions • 2. Fusion: This type of reaction involves two small nuclei coming together to form a larger nuclei. • This is how the sun works
2. Fusion • Nuclear fusion produces an enormous amount of energy, more than fission. • However the reaction is very unstable and dangerous. • Can only be contained in stars like the sun.