Louis Perez

25.2
Nuclear force: Is an attractive force that acts between all nuclear particles that are extremely
close together, such as protons and neutrons in a nucleus.
Band off stability: for elements of low atomic number below about 20, this ratio is about 1.
Above atomic number 20, stable nuclei have more neutrons than protons.
Positron: is a particle with the mass of an electron but a positive charge.
Half life: is the time required for one-half of the nuclei in a radioisotope sample to decay to
products.
All atomic nuclei, except those hydrogen atoms, consist of neutrons and two or more protons.
A nucleus may be unstable and undergo spontaneous decay for different reasons.
A neutron that emits an electron becomes a proton.
Other nuclei are unstable because they have too few neutrons relative to the number of protons.
These nuclei increase their stability by converting a proton to a neutron.
Transmutation: The conversion of an atom of one element into an atom of another element.
These are common in nature.
Rutherford’s experiment eventually led to the discovery of the proton. He and other scientist
noticed a pattern as they did different transmutations experiments.
Elements with the atomic number above 92 are transuranium elements. All of these elements are
radioactive, and undergo transmutation.
James Chadwick discovered the neutron in 1932, neutrons were produced when beryllium-9 was
bombarded with alpha particles.