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Nuclear Reactions• Fission • Fusion
There is a STRONG NUCLEAR FORCE that holds the neutron and protons together in the Nucleus.
CHEMICAL NUCLEAR
Occurs when bonds are broken or formed.
Occurs when nuclei emit particles and/or rays.
Atoms remained unchanged, though may be rearranged.
Atoms often converted into atoms of another element.
Involves valence electrons May involve protons, neutrons or electrons
Small energy changes HUGE energy changes
Reaction rates affected by temp and pressure
Reaction rate NOT normally affected temp and pressure
CHEMICAL NUCLEAR
Occurs when bonds are broken or formed.
Occurs when nuclei emit particles and/or rays.
Atoms remained unchanged, though may be rearranged.
Atoms often converted into atoms of another element.
Involves valence electrons May involve protons, neutrons or electrons
Small energy changes HUGE energy changes
Reaction rates affected by temp and pressure
Reaction rate NOT normally affected temp and pressure
CHEMICAL NUCLEAR
Occurs when bonds are broken or formed.
Occurs when nuclei emit particles and/or rays.
Atoms remained unchanged, though may be rearranged.
Atoms often converted into atoms of another element.
Involves valence electrons May involve protons, neutrons or electrons
Small energy changes HUGE energy changes
Reaction rates affected by temp and pressure
Reaction rate NOT normally affected temp and pressure
CHEMICAL NUCLEAR
Occurs when bonds are broken or formed.
Occurs when nuclei emit particles and/or rays.
Atoms remained unchanged, though may be rearranged.
Atoms often converted into atoms of another element.
Involves valence electrons May involve protons, neutrons or electrons
Small energy changes HUGE energy changes
Reaction rates affected by temp and pressure
Reaction rate NOT normally affected temp and pressure
CHEMICAL NUCLEAR
Occurs when bonds are broken or formed.
Occurs when nuclei emit particles and/or rays.
Atoms remained unchanged, though may be rearranged.
Atoms often converted into atoms of another element.
Involves valence electrons May involve protons, neutrons or electrons
Small energy changes HUGE energy changes
Reaction rates affected by temp and pressure
Reaction rate NOT normally affected temp and pressure
CHEMICAL NUCLEAR
Occurs when bonds are broken or formed.
Occurs when nuclei emit particles and/or rays.
Atoms remained unchanged, though may be rearranged.
Atoms often converted into atoms of another element.
Involves valence electrons May involve protons, neutrons or electrons
Small energy changes HUGE energy changes
Reaction rates affected by temp and pressure
Reaction rate NOT normally affected temp and pressure
Fission
Neutrons bombard nucleus
splitting nucleus
(from heavy to lighter)
release 2 things: neutrons and energy
Nuclear Power Plants• Fission is controlled by:
– releasing neutrons to start the chain reaction
– capturing neutrons to slow or stop the reaction.
ISOTOPES
Radioactivity
• Any process where the nucleus emits particles or energy
Nuclear Decay
ALPHA
- a particle that has 2 protons and 2 neutrons (helium) is released from an unstable nucleus.
Ex:
uranium – 238
Fission
BETA
- occurs when a neutron in the nucleus of a radioactive isotope splits into a proton and an electron.
Ex:
Carbon - 14
GAMMA
- involves the release of HIGH energy and radiation from the nucleus of the atom.
Protons, neutrons and electrons not affected.
Ex: nuclear power fuels
Chapter 19
Radioactivity and Nuclear Energy
14
: The decay series.
15
A representation of a Geiger-Müller counter.
16
Unstable nucleus.
17
Representation of a fission process.
18
Diagram of a nuclear power plant.
Copyright © by McDougal Littell. All rights reserved.
19
Schematic of the reactor core.
20
Radioactive particles and rays
vary greatly in penetrating power.
21
Diagram for the tentative plan for deep underground isolation of
nuclear waste.
An alpha particle is a Helium 4 nucleus (two protons and two neutrons). It is produced by nuclear fission in which a massive nucleus breaks apart into two
less-massive nuclei (one of them the alpha particle). This is a strong interaction process.
A beta particle is an electron. It emerges from a weak decay process in which one of the neutrons
inside an atom decays to produce a proton, the beta electron and an anti-electron-type neutrino.
A gamma particle is a photon. It is produced as a step in a radioactive decay chain when a massive
nucleus produced by fission relaxes from the excited state in which it first formed towards its lowest energy or ground-state configuration.
How Far Away?• Inverse Square Law
Half-Life
• Amount of time it takes for ½ the radioactive material to decay
E=mc2
• Eenergy• mmass• cspeed of light
– (3.0 x 108 m/s)
• Small mass=large output
Mass of proton and neutron in the nucleus is less than the same protons and neutrons separate?
Critical Mass• Minimum fissionable
isotopes needed to provide neutrons to sustain chain reaction
Smoke Detectors• Alpha emitters
– Charged• current with smoke• Am-241
Nuclear Medicine
• Used by >>1 in 3 admitted to hospital
• Biochemical & Physical changes occur in disease before anatomical can be identified
Radioactive Tracers
• Technetium-99– 6 hr half-life– Accumulate in cells
with rapid growth (tumors)
Gadolinium-153
• Accumulated in bone– Osteoporosis
Fusion
• Interior of sun – 15 million °C
• Nuclei combine– H ‘s combine to form He
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