Nuclear Reactions

Nuclear Fission and Fusion

In a nuclear reaction, the number of protons or neutrons in an atom changes so that the atom is changed from one element to another.

Radioactive decay. By 1899, Rutherford had shown that radioactive substances can emit two types of radiation, which he names alpha and beta. In 1900, French physicist Paul Villard discovered a third, more penetrating radiation, which he named gamma rays.
Fission reactions occur when nuclides split into smaller, lighter nuclei. There are two types of fission: spontaneous fission and stimulated (or induced) fission.
Nuclear fusion reactions occur when two or more nuclei travelling at very high speeds collide and join to form a new type of nucleus. The colliding nuclei must overcome strong repulsive forces, so requires very large amounts of energy.

Youtube clip: 5:52

Cognito - 4 min

Cognito - 3 min

FuseSchool - 4 min

FuseSchool - 5 min

The video uses the atomic mass unit (symbol: u) as the unit of mass of atoms and subatomic particles.

An atomic mass unit is defined as a mass equal to one twelfth the mass of an atom of carbon-12.
1 u = 1.66 × 10−27 kg (refer to SciPad p.70 Q.1)
Nuclear fission
Mass deficit
Binding energy

Tinyverse - 8 min

Perception - 6 min

Nuclear Fission Power Plants:

Most nuclear power station uses a neutron bombardment of uranium-235 to generate power.
The nuclear reactor is used to produce a controlled chain reaction.
The uranium fuel is encased in graphite.
The graphite core acts as a moderator. This slows down the neutrons released by the uranium fission reaction so they can be captured by other uranium-235 nuclei.