Radiocarbon dating
Teaching notes
Where does the resource fit?
• The resource is aimed as an activity to assist on the
consolidation of the learning of radiocarbon dating and
half life.
• OCR Gateway Additional Science B – Radiation for life.
• OCR 21st Century Additional Science A – Physics –
Radioactive materials.
• AQA Additional Science – Physics – Atoms and
radiation.
• Edexcel Additional Science – Physics – Advantage and
disadvantages of using radioactive materials.
How to use the resource
• The resource is in the form of a pdf file and can be
opened up with software such as adobe acrobat
reader.
• There are 2 pages to the resource.
• Page 1 (sheet 1): radioactive dating using carbon-14.
There is a table of data for activity against time. The
students are expected to draw a graph and answer the
questions provided.
• Page 2 (sheet 2): radioactive dating using usranium238. There is a table of data for % of U-238 left against
time. The students are expected to draw a graph and
answer the questions provided.
Answers
Radioactive dating using carbon-14
1.
2.
3.
•
•
4.
•
•
•
(sensible graph)
5,700 years
a) 13,500 years old
b) 750 years old
c) 31,750 years old
a) 1600 cps
b) 28 cps
c) 0 cps
d) 2900 cps
5. Not precise enough for
CSI. Activity will have
hardly decreased.
6. After 70,000 year
carbon-14 has fully
decayed, so anything
older cannot be
determined.
7. a) 11,400 years old
• b) 28,500 years old
8. a) 380 cps
• b) 200 cps
Answers
Radioactive dating using uranium-238
1.
2.
3.
•
•
4.
•
5.
•
6.
•
(sensible graph)
4.5 billion years
a) 5.9 billion years old
b) 0.25 billion years old
c) 2.5 billion years old
a) 70 %
b) 10 %
a) 25 %
b) 3.5 %
a) 3 half-life’s
b) 4 half-life’s
7. a) The atomic mass
reduces by 4 to account
for the alpha particle
emitted (2 protons and 2
neutrons)
• b) U-234 > Th-230,
Th230 > Ra-226, Ra-226
> Po-218, Po-218 > Pb214, Po-214 > Pb-210,
Pb-210 > Pb-206
8. Th-234 > Pa-234, pb-214
> Bi-214, Bi-214 > Po214, Pb-210 > Bi-210, Bi210 > Po-210