Page 23 - Chemistry_Form_2

Chemistry
for Secondary Schools

applications, including determining the age of ancient objects using carbon-14,
treating diseases in hospitals, tracking how plants absorb nutrients in the soil, and
producing electricity for everyday uses.

Carbon dating: Finding the age of ancient items
FOR ONLINE READING ONLY
Scientists use carbon-14 to determine the age of ancient objects. Carbon-14 is a
radioactive isotope of carbon that slowly breaks down over time. When a plant
or animal dies, it stops taking in carbon-14 from the air. Scientists measure how
much carbon-14 is left in bones, wood, or fossils to estimate the number of years
that have passed since the organism died. Carbon dating helps archaeologists and
historians learn about the past, including the age of ancient human tools, animal
fossils, and historical items.

Tracers in medicine, industry, and agriculture

Some radioactive isotopes are used as tracers that help scientists track movements
or processes inside the body, in the environment, or in industrial systems.

(a) Medicine: Diagnosing and treating diseases

Iodine-131 is used in hospitals to check how the thyroid gland works. When
a small dose of iodine-131 is administered to a patient, the radiation emitted
by the iodine helps to create images of the thyroid. Special machines detect
the radiation to help diagnose thyroid problems. The radiation also helps to
shrink or destroy damaged thyroids cells leading to the treatment of thyroid
related diseases.

(b) Agriculture: Studying how plants absorb nutrients
Phosphorus-32 is used to track how plants take in nutrients from the soil.
Scientists use it to improve fertilisers and help farmers grow healthier crops.

(c) Industrial and environmental applications

Some isotopes, such as tritium -3 tracks how water moves underground.
This allows scientists to understand the sources of drinking water. Chlorine
isotopes are used to study the movements of chlorine in water sources such
as rivers, lakes, and underground water. Sodium-24 is used to detect leaks in
underground pipes. This isotope is made artificially.

16 Student’s Book Form Two

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