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C–14 and C–12 are both isotopes of carbon - Leaving Cert Physics - Question vii and viii - 2022
Question vii and viii
C–14 and C–12 are both isotopes of carbon. What are isotopes? The ratio of C–14 to C–12 in a sample from an archaeological artefact is found to be one quarter the r... show full transcript
Worked Solution & Example Answer:C–14 and C–12 are both isotopes of carbon - Leaving Cert Physics - Question vii and viii - 2022
Step 1
What are isotopes?
Answer
Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons. This difference in neutrons results in different atomic masses but retains the same chemical properties. For example, carbon-14 (C–14) and carbon-12 (C–12) are both isotopes of carbon, where C–14 has two more neutrons than C–12.
Step 2
Is the artefact from the Bronze Age? Justify your answer.
Answer
To determine if the artefact is from the Bronze Age, we must analyze the ratio of carbon isotopes. In a living tree, the ratio of C–14 to C–12 is constant. If the artefact's C–14 to C–12 ratio is one quarter of that found in a living tree, it suggests that the artefact is significantly older.
Considering that the half-life of C–14 is approximately 5730 years, the presence of just one quarter of the original C–14 indicates that approximately two half-lives have passed. This means the artefact is likely over 11,000 years old, which is well beyond the Bronze Age (approximately 3300 to 1200 BCE). Therefore, we can conclude that the artefact is not from the Bronze Age.