## Sunday, 4 January 2015

### 2.3 Isotopes and Their Importance

Isotopes
■ Isotopes
 ► Definition: Atoms of the same elements with the same proton number but different nucleon numbers. ► Definition: Atoms of an element with the same number of protons but different number of neutrons. ► The animation below shows examples of isotopes.
■ Isotopes of an element
 ► Same chemical properties because they have the same electron arrangement. ► Different physical properties due to the different number of neutrons. ► This video contains information about isotopes of an element.
 ► Unstable isotopes which emit radioactive rays.

Contoh latihan 2.3(a)
Complete the number of subatomic particles for isotopes of oxygen.
Symbol Number of protons Number of electrons Number of neutrons
Oxygen -16, $\begin{array}{c}16\\ 8\end{array}O$ 8 8 8
Oxygen -17, $\begin{array}{c}17\\ 8\end{array}O$ 8 8 9
Oxygen -18, $\begin{array}{c}18\\ 8\end{array}O$ 8 8 10

The uses of isotopes in daily life
■ Medical
 ► Gamma rays from cobalt-60 are used to kill cancer cells. ► Iodine-131 are injected into patients to detect thyroid glands. ► Medical instruments are sterilized using gamma rays.
■ Agriculture
 ► Carbon-14 is used to study the path of carbon in photosynthesis of plants. ► Pests control by genetic mutation.
■ Industry
 ► Paper thickness control. ► Isotopes sodium-24 is used to detect leakage of underground pipes.
■ Archeology: Radioisotope carbon-14 is used to study the age of ancient artifacts.
■ Food preservation: Extending the shelf-life of food by gamma radiation.
■ Food industry: Preventing the germination of potatoes and vegetables.
■ This video contains information about the uses of isotopes.