Chapter 28 Nuclear Chemistry

Nuclear Radiation Nuclear Transformations Fission and Fusion Radiation in Your Life

Ch 28.1 Nuclear Radiation

Radioactivity Types of Radiation

Radioactivity

Radioisotopes – an isotope that has an unstable atomic nucleus and undergoes radioactive decay

Always accompanied by large emissions of energy

Not affected by temp., pressure, or catalysts Can not speed up or slow down the reaction or

turn off

Radioactivity

Marie Curie – (1867-1934) named the process

Process by which unstable atomic nuclei achieve stability

Won Nobel Peace Prize – 1903 along with Pierre Curie and Antoine Henri Becquerel

Radiation

Penetrating rays and particles emitted by a radioactive source

Types of Radiation

Alpha Beta Gamma

Alpha

Helium nuclei emitted from a radioactive source

Alpha particles Contain 2 protons and 2 neutrons and

have a double positive charge 4

2He or Can be stopped by a sheet of paper or

your skin

Beta

Fast moving electrons formed by the decomposition of a neutron

Beta Particles 0

-1e or Can be stopped by aluminum foil or pieces

of wood

Gamma

High energy electromagnetic radiation No mass, no charge Can almost be stopped by several feet of

concrete or several inches of lead

Chernobyl

April 26, 1986 at 1:23:44am Reactor 4 exploded Released 30-40 times the amount of

radiation as bombing Japan did

Chapter 28.2 Nuclear Transformations

Nuclear Stability and Decay Half – Life Transmutation Reactions

Nuclear Stability and Decay

1500 different nuclei, only 264 are stable For low atomic number (up to 20), the ratio

of protons to neutrons is 1(ratio of stability) 12

6C 147N

Atomic numbers above 20, have a ratio of protons to neutrons of 1.5(ratio of stability) 206

82Pb

Beta Emissions

6629Cu 66

30Zn + 0-1e

146C 14

7N + 0-1e

Positron

Particle with the mass of an electron, but a positive charge

0+1e

85B 8

4Be + 0+1e

Alpha Emission

All nuclei with an atomic number greater than 83 are radioactive

20482Pb 200

80Hg + 42He

22688Ra 222

86Rn + 42He

Half Life

The time required for one half of the nuclei of a radioisotope sample to decay to products

Artificial Radioisotopes

Usually have very short half lives Used in nuclear medicine

PET Scan - Positron Emission Tomography

Brain Function

Thyroid TumorsDog

Iodine 131

Bone Fractures

Technetium

Radioactive Isotope UseC-14 Used to determine the age of biological remains (archaeology)I-131 Used to detect and cure hyperthyroidism (overactive thyroid)Co-60 Used as a source of radiation for radiotherapy of cancerTc-99m Used to image blood vessels, especially in the brain, to detect tumorsPu-239 Used as a highly fissionable fuel source for nuclear power or nuclear weaponsAm-241 Used in tiny amounts in smoke detectors as a source of ions to make a currentU-235 Used as fissionable fuel source for nuclear power or nuclear weaponsU-238 Used to determine the age of uranium-containing rock formations (geology)