Nuclear Chemistry

Chad Van

Every

A radioisotope is a radioactive isotope of an element. Ex: A natural radioisotope of Uranium-238 is Uranium-

235 Radioisotopes are constantly decaying into other

elements. The half-life of a radioactive isotope is the time it

takes for one half of a sample of that isotope to decay. Question: If you have 8 grams of an element and its

half-life is 1 day, how many grams are left after 3 days?

Radioisotopes

- Carbon-14 is a well known radioactive isotope that is used in radiocarbon dating.

- It has a half-life of 5730 years.- Based on its half-life, scientists

can determine the age of plant, animal, and object remains.

-Note: this works up to 30,000 years

Radioisotopes

One way to make a stable nucleus unstable is with a nuclear bombardment reaction. An atom is bombarded with a stream of

particles such as alpha (α) particles, forming a new nucleus

Ex: α + N → O + H

Radioisotopes

Biological Effects of Radiation• The SI unit of radioactivity is the becquerel,

named after Henri Becquerel.• A more widely used unit is the curie (Ci), named

after Pierre and Marie Curie.• The rem (roentgen equivalent for man) measures

radiation exposure in humans.

Biological Effects of Radiation

• A dosimeter measures the total amount of radiation that a person has received.

• A Geiger counter detects radiation.• High energy radiation (such as gamma)

forms free radicals inside the body and can destroy tissue.• NOTE: Radiation damage may affect an

organism directly or it may affect the organism’s offspring, if reproductive cells are affected.

Biological Effects of Radiation In spite of the hazards of radiation, radioisotopes

are very beneficial in medicine, agriculture, and industry.

• --- Radiotracers use radioactive substances to follow a specified substance as it moves through a natural system.

• --- Radiotherapy uses radioactive substances to help treat cancer.

• --- Radiation can be used to help preserve foods such as strawberries.

Harnessing the NucleusIn a nuclear fission reaction, a large nucleus

is split into two smaller nuclei of approximately equal mass.Ex: n + U → U → Ba + Kr + 3n

***Mass and charge are conserved***Ex: atomic bombMassive amounts of energy are released and

can be calculated by the equation: E = When one fission reaction occurs, many more

follow behind the first, creating a chain reaction.

Harnessing the NucleusNuclear reactors are not able to explode like

an atomic bomb because they are regulated by control rods that slow down the speed of the neutrons.

Harnessing the NucleusIn a nuclear fusion reaction, two small nuclei

join to form a large nucleus.Ex: H + H → He + n

***Mass and charge are conserved***Ex: the sunFusion reactions are still in the experimental

stage because they are very difficult to create and control.

GOOD LUCK ON THE REGENTS!

☺Any questions…

Let me know