Radioactivity and Nuclear Rx GlencoePS

Radioactivity and Nuclear Reactions : 

Radioactivity and Nuclear Reactions Week 26 Ch. 18 pg 534

strong force : 

strong force Causes the attraction protons (+) and neutrons in the nucleus one of the four basic forces in nature (the others being gravity, the electromagnetic force, and the weak nuclear force). As its name implies, it is the strongest of the four. The strong nuclear force is created between nucleons by the exchange of particles called mesons. As long as this meson exchange can happen, the strong force is able to hold the participating nucleons together.

radioactivity : 

radioactivity The process in which the nucleus decays and gives off matter and energy (gamma rays), all nuclei with more than 83 protons are radioactive

Henri Becquerel, 1896 : 

Henri Becquerel, 1896 Discovered uranium was radioactive by leaving it on photographic paper and finding the paper to be exposed

alpha particle : 

alpha particle A helium atom with no electrons, can be stopped by a sheet of paper, can cause disease

beta particle : 

beta particle Electron emitted from the nucleus of a radioactive atom, caused by the weak force, stopped by aluminum foil, can cause disease In beta decay, a neuton converts to a proton emitting a beta particle in the process. The beta particle is identical to an ordinary electron.

gamma rays : 

gamma rays The most penetrating form of nuclear radiation, stopped by thick pieces of lead and concrete

half-life : 

half-life The amount of time it takes for half the nuclei of a sample to decay We have a sample of rock which we analyze and find that it has 1/4 of its original U238. U238 has a half-life of 4.5 billion years. In one half-life (=4.5billion years), 50% = 1/2 of the U238disappears. In the second half-life, half of the remaining half would disappear so 1/2 of 1/2 = 1/4 (25%) would remain. Therefore our rock must have an age of 2 x 4.5 billion years or 9 billion years (note—no rock any where near this old has been found in the Solar System!).

radioactive dating : 

radioactive dating Estimates the age of a material by measuring the amount of decay present

Radiation detectors : 

Radiation detectors detect alpha and beta particle radiation - cloud chamber, bubble chamber, electroscopes

Geiger counter : 

Geiger counter Measures radiation

Background radiation : 

Background radiation Low level radiation emitted mainly by naturally occurring matter, mainly radon

nuclear fission : 

nuclear fission The splitting of a nucleus into several smaller nuclei

chain reaction : 

chain reaction A series of repeated fission reactions caused by the release of neutrons in each reaction

critical mass : 

critical mass The smallest amount of material required for a sustained chain reaction to occur

nuclear fusion : 

nuclear fusion When two nuclei with low masses fuse to form one nucleus of larger mass, opposite of fission, ex. the sun

tracer : 

tracer Using radioactive isotopes to find or keep track of molecules in an organism

And now for the quiz : 

And now for the quiz

Slide 19: 

Electron emitted from the nucleus of a radioactive atom, caused by the weak force, stopped by aluminum foil, can cause disease In beta decay, a neuton converts to a proton emitting a beta particle in the process. The beta particle is identical to an ordinary electron.

Slide 20: 

Measures radiation

Slide 21: 

Low level radiation emitted mainly by naturally occurring matter, mainly radon

Slide 22: 

Discovered uranium was radioactive by leaving it on photographic paper and finding the paper to be exposed

Slide 23: 

A helium atom with no electrons, can be stopped by a sheet of paper, can cause disease

Slide 24: 

When two nuclei with low masses fuse to form one nucleus of larger mass, opposite of fission, ex. the sun

Radioactivity and Nuclear Reactions : 

Radioactivity and Nuclear Reactions

Slide 26: 

Causes the attraction protons (+) and neutrons in the nucleus one of the four basic forces in nature (the others being gravity, the electromagnetic force, and the weak nuclear force). As its name implies, it is the strongest of the four. The strong nuclear force is created between nucleons by the exchange of particles called mesons. As long as this meson exchange can happen, the strong force is able to hold the participating nucleons together.

Slide 27: 

The process in which the nucleus decays and gives off matter and energy (gamma rays), all nuclei with more than 83 protons are radioactive

Slide 28: 

The amount of time it takes for half the nuclei of a sample to decay We have a sample of rock which we analyze and find that it has 1/4 of its original U238. U238 has a half-life of 4.5 billion years. In one half-life (=4.5billion years), 50% = 1/2 of the U238disappears. In the second half-life, half of the remaining half would disappear so 1/2 of 1/2 = 1/4 (25%) would remain. Therefore our rock must have an age of 2 x 4.5 billion years or 9 billion years (note—no rock any where near this old has been found in the Solar System!).

Slide 29: 

Estimates the age of a material by measuring the amount of decay present

Slide 30: 

detect alpha and beta particle radiation - cloud chamber, bubble chamber, electroscopes

Slide 31: 

Using radioactive isotopes to find or keep track of molecules in an organism

Slide 32: 

The most penetrating form of nuclear radiation, stopped by thick pieces of lead and concrete

Slide 33: 

The splitting of a nucleus into several smaller nuclei

Slide 34: 

A series of repeated fission reactions caused by the release of neutrons in each reaction

Slide 35: 

The smallest amount of material required for a sustained chain reaction to occur

Mahalo!! : 

Mahalo!!