Skill 20.5 Analyze the properties of an atomic nucleus that affect its stability

Skill 20.5 Analyze the properties of an atomic nucleus that affect its stability. 

Some nuclei are unstable and emit particles and electromagnetic radiation. These emissions from the nucleus are known as radioactivity the unstable isotopes are known as radioisotopes and the nuclear reactions that spontaneously alter them are known as radioactive decay. Particles commonly involved in nuclear reactions are listed in the following table  

Particle Neutron Proton Electron Positron Alpha particle Beta particle Gamma rays 

The half-life of a reaction is the time required to consume half the reactant. 

The rate of radioactive decay for an isotope is usually expressed as a half-life. Solving these problems is straightforward if the given amount of time is an exact multiple of the half-life. For example, the half-life of Pa is 27.0 days. This 

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