Download 25.2 section summary

SECTION SUMMARY
25.2 Nuclear Transformations Summary:
Nuclei that lie outside the band of stability undergo spontaneous radioactive
decay. Nuclei with too many neutrons undergo beta emission as neutrons are
converted to protons. A positron is a particle with a positive charge and the mass of
an electron.
Every radioisotope decays at a characteristic rate. A half-life is the time required
for one half of the nuclei in a radioisotope to decay. The product nuclei may or may
not be radioactive. Half-lives vary from fractions of a second to billions of years.
The conversion of atoms of one element to atoms of another is called
transmutation. This process can occur by radioactive decay or when particles
bombard the nucleus of an atom. All of the elements with atomic numbers above 92,
trasuranium elements have been synthesized in nuclear reactors or accelerators.
Transmutation reaction sometime occurs spontaneously.
25.2 Nuclear Transformations Vocabulary Terms:
nuclear force:
an attractive force that acts between all nuclear
particles that are extremely close together, like
protons and neutrons in a nucleus
band of stability:
the location of stable nuclei on a neutron vs. proton
plot
positron:
a particle with the mass of an electron but a positive
charge
half-life (t1/2):
the time required for one-half of the nuclei of a
radioisotope sample to decay to products
transmutation:
the conversion of an atom of one element to an
atom of another element
transuranium element:
any elements in the periodic table with atomic
number above 92, the atomic number of uranium
The End of the Summary