alpha beta and_gamma
TRANSCRIPT
Radioactivity and radioisotopes
A very brief history of the discovery of radioactivity
Henri Bequerel (1852-1908)
Dear Marie, do you remember those uranium compounds that glow when I put them under sunlight? Well, guess what I found out last night as I put them in my drawer… in the same drawer I had a key on top of a film plate. When I developed the film the image of the key was impressed on it, although the
film was wrapped! These compounds must emit invisible rays that penetrate certain materials. I think I’ll call them Radioactivity.
Don’t say more dear Professor! I have taken on the work you have passed on to me and I have already discovered two new elements more radioactive than uranium, polonium and radium. To isolate 1 g of radium I had to buy a tonne of pitchblende and separate the radium. The amazing thing is that the radium
is about one million times more radioactive than uranium! Marie Curie (1867-1934)
Hey guys, thank you for this stuff! Now that we know so much I can find out the nature of this radioactivity pal! In fact, I have already discovered that there are at least two kinds of radiation. I’ve called the first alpha. This gets easily
absorbed and it’s positively charged. The second is beta, it is more penetrative and has negative charge.
Ernest Rutherford (1871-1937)
What is radioactivity?Radioactivity is the spontaneous emission of energy and
particles due to the breaking down (disintegrating) of the nuclei of unstable atoms.
Particles
Energy
What is radioactivity?It is not known what causes this spontaneous decay of
the nucleus. However we know the nature of the radioactivity. It can manifest in three forms; alpha and beta particles and gamma radiation.
Beta particles
Gamma rays
Alpha particles
What is radioactivity?Suggest reasons why the rate of radioactive decay seems not to be affected by
chemical reactions, temperature, or pressure.
• Chemical reactions involve only electrons within atoms and energy of the order of a few eV.
• Even at high temperatures of 6000 K (surface temperature of the Sun) the vibration energy of the atoms only about 1 eV.
• But binding energies of nuclei are of the order of 10 MeV (10000000 eV).
The three types of radiation
Alpha () Beta () Gamma ()
Nature
Charge
Mass
Speed
Ionizing effect
Most dangerous
Use this table to find information about and to compare , and radiation
The three types of radiation
Alpha () Beta () Gamma ()
Nature
It’s a nucleus of helium . Two protons and two neutrons
It’s an electron
e-
It’s an electromagnetic wave
Charge
Mass
Speed
Ionizing effect
Most dangerous
Use this table to find information about and to compare , and radiation
He42
The three types of radiation
Alpha () Beta () Gamma ()
Nature
It’s a nucleus of helium . Two protons and two neutrons
It’s an electron
e-
It’s an electromagnetic wave
Charge +2 -1 0
Mass
Speed
Ionizing effect
Most dangerous
Use this table to find information about and to compare , and radiation
He42
The three types of radiation
Alpha () Beta () Gamma ()
Nature
It’s a nucleus of helium . Two protons and two neutrons
It’s an electron
e-
It’s an electromagnetic wave
Charge +2 -1 0
Mass Relatively large Very small No mass
Speed
Ionizing effect
Most dangerous
Use this table to find information about and to compare , and radiation
He42
The three types of radiation
Alpha () Beta () Gamma ()
Nature
It’s a nucleus of helium . Two protons and two neutrons
It’s an electron
e-
It’s an electromagnetic wave
Charge +2 -1 0
Mass Relatively large Very small No mass
Speed Slow Fast Speed of light
Ionizing effect
Most dangerous
Use this table to find information about and to compare , and radiation
He42
The three types of radiation
Alpha () Beta () Gamma ()
Nature
It’s a nucleus of helium . Two protons and two neutrons
It’s an electron
e-
It’s an electromagnetic wave
Charge +2 -1 0
Mass Relatively large Very small No mass
Speed Slow Fast Speed of light
Ionizing effect
Strong Weak Very weak
Most dangerous
Use this table to find information about and to compare , and radiation
He42
The three types of radiation
Alpha () Beta () Gamma ()
Nature
It’s a nucleus of helium . Two protons and two neutrons
It’s an electron
e-
It’s an electromagnetic wave
Charge +2 -1 0
Mass Relatively large Very small No mass
Speed Slow Fast Speed of light
Ionizing effect
Strong Weak Very weak
Most dangerousWhen source is inside the body
When source is outside the body
When source is outside the body
He42
Use this table to find information about and to compare , and radiation