Question

What is the isotope symbol for $ iodine - 131 $ ?

Answer 1

Hint : Isotopes are the atoms of the same element of the modern periodic table which have different mass numbers (atomic mass) and same atomic number value. In these types of atoms, the number of electrons and protons remain the same but the number of neutrons are different in all the isotopes which makes the mass number different.

Complete Step By Step Answer:
Isotopes are the atoms of the same element of the modern periodic table which have different mass numbers (atomic mass) and same atomic number value. Therefore, we can say that in these types of atoms, the number of electrons and protons remain the same but the number of neutrons are different.
Generally symbol for any atom or element is represented as:
 $ {}_Z^AX $
Where, X is the chemical symbol of the element.
A is the atomic mass of the element.
Z is the atomic number of the element.
Hence if we take $ iodine - 131 $ , in this the chemical symbol of iodine element is an atomic mass or mass number (A) of iodine is given as $ 131 $ .
And we know that, atomic number (Z) of the iodine element is $ 53 $ .
Hence, we put these values in the above chemical notation, we get
 $ {}_{53}^{131}I $
Therefore, the isotope symbol for $ iodine - 131 $ is $ {}_{53}^{131}I $ .

Note :
$ Iodine - 131 $ is a radioactive isotope of Iodine element with a half-life of eight days. It is a very useful isotope as it has some medicinal applications. It is used to monitor the functioning of the thyroid gland. It is also used to treat goitre disease and thyroid cancer. It is used to locate tumors in the brain and liver.