Everything Science Grade 11

4.8 CHAPTER 4. ATOMICNUCLEI

• thyroid gland


• kidneys


• brain
  In each case, try to findout:

1. which radioisotope is used


2. what the sources of this radioisotope are


3. how the radioisotopeenters the patient’s bodyand how it is monitored

Activity: Using radiocarbon dating

Radiocarbon dating hasplayed an important role in uncovering manyaspects of South

Africa’s history. Read the following extract froman article that appearedin Afrol news on 10th

February 2007 and thenanswer the questions that follow.

The world famous rockart in South Africa’s uKhahlamba-Drakensberg,a World

Heritage Site, is three times older than previouslythought, archaeologistsconclude

in a new study. The more than 40,000 paintingswere made by the San people some

3000 years ago, a new analysis had shown.

Previous work on the age of the rock art in uKhahlamba-Drakensbergconcluded

it is less than 1,000 years old. But the new study - headed by a South African

archaeologist leading ateam from the University of Newcastle upon Tyne (UK) and

Australian National University in Canberra - estimates the panels were created up to

3,000 years ago. They used the latest radio-carbon dating technology.

The findings, publishedin the current edition ofthe academic journal ’South African

Humanities’, have ”major implications for our understanding of how therock artists

lived and the social changes that were taking place over the last threemillennia,”

according to a press release from the British university.

Questions:

1. What is the half-life of carbon-14?


2. In the news article, what role did radiocarbondating play in increasingour knowledge of
   South Africa’s history?


3. Radiocarbon datingcan also be used to analyse the remains of once-living organisms.
   Imagine that a set of bones are found betweenlayers of sediment androck in a remote
   area. A group of archaeologists carries out a series of tests to try to estimate the age of the
   bones. They calculate that the bones are approximately 23 040 years old.
   What percentage of theoriginal carbon-14 musthave been left in the bones for them to
   arrive at this estimate?

4.8 Nuclear Fission ESBAP

Nuclear fission is a process where thenucleus of an atom is split into two or more smaller nuclei,

known as fission products. The fission of heavy elements is an exothermic reaction and huge amounts

of energy are released in the process. This energy can be used to produce nuclear power or to make

nuclear weapons, both of which we willdiscuss a little later.