chapter9 Flashcards
radioactivity
the process by which an unstable nucleus emits one or more particles, OR energy in the form of electromagnetic radiation
nuclear radiation
the particles that are released from the nucleus during radioactive decay.
After the changes in the nucleus, the element can transform into
a different isotope of the same element or into an entirely different element.
alpha particle
a positively charged atom that is released in the disintegration of radioactive elements and that consists of two protons and two neutrons i.e. He nucleus. massive but NOT very energetic.
Alpha particles can Ionize matter.
beta particle
a charged (fast moving) electron emitted during certain types of radioactive decay, such as beta decay.
Beta particles can ionize matter.
gamma radiation
high energy photon released by a nucleus during fission, and radioactive decay. Very high energy, and hazardous. Can penetrate 7mm of Pb.
Gamma rays
High energy photons/EM radioation. Can ionize other matter. Very energetic
Neutron emission
emission of a neutron from an unstable particle.
NO charge —> no matter ionization, as such they travel far through matter.
alpha decay
A nucleus gives up two protons and two neutrons in the form of a He nucleus.
2 protons & 2 neutrons form a He nucleus.
beta decay
emission of an electron whereby a neutron decays into a proton and electron.
So a nucleus gains a proton and loses a neutron, as it emits an electron.
half life
the time required for half of a sample of a radioactive substance to disintegrate by radioactive decay, or by natural processes.
Nuclear Radiation
may emitt alpha particles, beta particles, gamma rays, and neutrons.
gamma radiation
electomagetic wave with lots of energy (high energy photon).
Neutrons help keep nuclei together
the nucleus is held together by the attractions between protons and neutrons. These forces are greater than the electric repulsion among the protons alone.
Unstable Nuclei: # of P > 83
Nuclei with more than 83 protons are always unstable, no matter how many neutrons they have.
Fission
the process by which a nucleus splits into two or more fragments and releases neutrons and energy.
mass defect
the total mass of a nucleus is less than the sum mass of all neutrons and protons comprising it.
Nuclear Chain Reaction
continuous series of nuclear fission reactions.
Critical Mass
the minimum mass of a fissionable isotope that provides the number of neutrons needed to sustain a chain reaction.
Nuclear Fusion
the process in which light nuclei combine at extremely high temperatures to, forming heavier nuclei and releasing energy.
REM
the quantity of ionizing radiation that does as much damage to human tissue as 1 roentgen of high voltage X rays does.
