Transcript Radiation-ch 7.1 and 7.2

7.2-Half-Life
7.3- Nuclear Rx
Hulk smash! GRR! I’m
going to teach you about
half-life and nuclear Rx!
What is a half-life?
The rate of radioactive decay can be
compared using a quantity called half-life
 Ex. The half-life of strontium-90 is 29
years. If you have 10.0g strontium-90
today, 29 years from now, you will have
5.0g left.

Isotopes
An isotope of an element have nuclei
with the same number of protons (the
same "atomic number") but different
numbers of neutrons. Therefore isotopes
have different "mass numbers", which
is the total number of nucleons (protons
plus neutrons).
Mass number= atomic number+ neutrons

Isotopes(pg2)
Parent isotope: the isotope that
undergoes radioactive decay
 Daughter isotope: The stable product of
radioactive decay

Subatomic Particles
Quiz Time!!!
1.
2.
3.
4.
What is an isotope?
What are the two types of isotopes?
What is a half-life?
Name 3 subatomic particles and their
symbols.
Carbon Dating
We can measure how the radioactivity in
plant or animal remains has changed over
time and calculate the age.
 All organisms on Earth contain carbon.
 Radiocarbon dating is the process of
determining the age of an object by
measuring the amount of carbon-14 in
that object.

Carbon Dating(pg.2)
Carbon’s isotopes include carbon-12 and
carbon-14
 When an organism is alive, the ratio of
carbon-14 atoms to carbon-12 atoms
remains nearly constant.
 When an organism dies, that ratio
decreases with time.
 Hence, radiocarbon dating was born.

Decay Curve
A decay curve is a curved line on a graph
that shows the rate at which radioisotopes
decay.
 Ex.

Radioactive Decay
Radioactive decay is the process in which
unstable nuclei lose energy by emitting
radiation.
 Isotopes that are capable of radioactive
decay are called radioisotopes.

Radioactive Decay
Alpha Radiation
 An alpha particle is a positively charge atomic particle
that has the same combination of particles as the
nucleus of a helium atom.
 It has an electrical charge of 2+
 A single sheet of paper stops alpha particles

Symbol:
Video Time!!!

http://www.youtube.com/watch?v=je9_Rt
whjWg
Radioactive Decay
Beta Radiation
 A beta particle is an electron.
 It has an electrical charge of -1.
 It requires a thin sheet of aluminum foil to block.
 Symbol:
Video Time!!

http://www.youtube.com/watch?v=tNDf2JY6Pk
Radioactive Decay
Gamma Radiation
 It consists of high-energy, shortwavelength radiation.
 Blocked by thick blocks of dense materials
i.e. lead and concrete.
 Gamma decay results from a
redistribution of energy within the nucleus.
 Symbol:
Video Time!!!

http://www.youtube.com/watch?v=PW_K
NP3glls
Can you think of an
example of a
product of gamma
radiation?
Fission vs Fusion
Fission is the splitting of a large atom
into two or more smaller ones.
 Fusion is the fusing of two or more
lighter atoms into a larger one.

QUIZ TIME!!!
Name the 3 different radiation types.
 Define fission.
 Define fusion.
 True or false: Gamma radiation is a stream
of gamma particles.
