Three Types of Atomic Nuclear ChangesThree Types of Atomic Nuclear Changes

Radioactive decay- Radioactive decay- atoms “break down” by atoms “break down” by emitting ionizing radiationemitting ionizing radiation

FissionFission- splitting large atoms (like uranium)- splitting large atoms (like uranium) First atomic bombsFirst atomic bombs All nuclear power plantsAll nuclear power plants

FusionFusion- fusing atoms together (like hydrogen)- fusing atoms together (like hydrogen) ““H-Bomb”H-Bomb” Sun and all other starsSun and all other stars 100 million degrees Celsius to begin reaction100 million degrees Celsius to begin reaction

Nuclear Changes: Radioactive DecayNuclear Changes: Radioactive Decay

Natural radioactive decay: unstable isotopes Natural radioactive decay: unstable isotopes spontaneously emit fast moving chunks of spontaneously emit fast moving chunks of matter (matter (alphaalpha oror beta particlesbeta particles), high-energy ), high-energy radiation (radiation (gamma raysgamma rays), or both at a fixed ), or both at a fixed rate.rate. Radiation is commonly used in Radiation is commonly used in energy productionenergy production

and and medical applicationsmedical applications.. The rate of decay is expressed as a The rate of decay is expressed as a half-lifehalf-life (the (the

time needed for one-half of the nuclei to decay to time needed for one-half of the nuclei to decay to form a different isotope).form a different isotope).

Nuclear Changes: FissionNuclear Changes: Fission

Nuclear fissionNuclear fission: : nuclei of certain nuclei of certain isotopes with large isotopes with large mass numbers are mass numbers are split apart into split apart into lighter nuclei when lighter nuclei when struck by neutrons.struck by neutrons.

Figure 2-9Figure 2-9

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235

Uranium-235 Fig. 2-6, p. 28

Neutron

Uranium-235

Energy

Fissionfragment

Fissionfragment

n

n

n

n

n

n

Energy

Energy

Energy

Stepped Art

Nuclear Changes: FusionNuclear Changes: Fusion

Nuclear fusionNuclear fusion: two isotopes of light elements : two isotopes of light elements are forced together at extremely high are forced together at extremely high temperatures until they fuse to form a heavier temperatures until they fuse to form a heavier nucleus.nucleus.

Figure 2-10Figure 2-10

Fig. 2-10, p. 42

Neutron

+

Hydrogen-2(deuterium nucleus)

Hydrogen-3(tritium nucleus)

+

Proton Neutron

100million °C

Energy

+

Helium-4 nucleus

ProductsReaction

ConditionsFuel

+

ENERGYENERGY

EnergyEnergy is the ability to do work and transfer is the ability to do work and transfer heat.heat. Kinetic energyKinetic energy – –

• energy in motionenergy in motion heat, electromagnetic radiationheat, electromagnetic radiation

Potential energyPotential energy – – • stored for possible usestored for possible use

batteries, glucose moleculesbatteries, glucose molecules