Science Form 3 Chapter 8

CHAPTER 8

Radioactive

Author:
Zakirah, Iqmal, Haris & Hanim











8.2 Atom and Nucleus

According to Dalton’s Atomic Theory, an atom is the smallest particle and cannot be further devided.
However, the development of scince has succeeded in finding particles that are even smaller called
protons, electrons and neutrons.
Structure of Atom

Formation of Positive Ions and Negatives Ions
When an atom loses or gains electrons, the atom becomes a charged particle known as ion.
POSITVE ION
An atom that loses electrons forms a positive ion ( cation ).
NEGATIVE ION
An atom that gains electrons forms a negative ion ( anion ).



USES OF RADIACTIVE RADIATION

ARCHEOLOGY / GEOCHRONOLOGY

- Carbon – 14 is used by archaeologist to determine the age
of fossils and artifacts.

- This method is known as carbon-14 dating.

INDUSTRY

- Beta radiation is used to control the thickness of metal sheets

AGRICULTURE

- Phosphorus-32 is used to determine the absorption rate of
phosphate fertiliser in plants.

MEDICAL

- Caesium-137 or cobalt-60 are used to kill cancer cells
without surgeries.

- Technetium-99 is used to treat tumours in the brain.

FOOD PRESERVATION

- Radura logo is used to label food preserved using
radioactive radiation such as gamma rays to kill bacteria in
the food.