2. The stability of the nucleus causes an isotope of an atom to be radioactive or not. If the nucleus is unstable, it is called radioactive and will break up until it becomes a stable nucleus. Each time the nucleus breaks up, you actually get a new element (only time in chemistry that this occurs) and a particle of radioactive decay (alpha particle, beta particle, gamma ray). Humans have found a way for naturally stable nucleii to break up, it is called induced or artifical radioactivity. The ratio of neutrons to protons indicates the stability of the nucleus of the isotope.
3. The protons (and neutrons) are held closely together in the nucleus by the binding force/energy (binding energy). Since protons all have positive charges, one would assume that you needed the binding energy (which is a lot of energy since the distance between protons are so small) for the nucleus to be held together. This large amount of energy comes from the loss of a small amount of mass, called mass defect, (via Einstein's equation, E = mc2) when the isotope is created. Therefore, if you added all the masses of the individual subatomic particles of the isotope (protons,electrons and neutrons) and compared it to the actual mass of the isotope, you would see that the actual mass of the istope is slightly less massive. Hence, when this mass is converted directly into energy, you have the binding energy value.
Notes from Section 26.1 Radioactivity (Addison Wesley Chemistry)
Antoine Becquerel -
Marie / Pierre Curie -
Def. radioactivity -
Def. radioisotopes -
Def. radioactive decay -
Notes from Section 26.3 Nuclear Stability (Addison Wesley Chemistry)
How many stable isotope _________ out of 1500 different istopes in all known elements?
Stability of isotopes in low atomic number?
Stability of isotopes in high atomic number?
Notes from Section 26.5 Transmutation Reactions (Addison Wesley Chemistry)
Def. transmutation -
Def. transmutation elements -