Question

Calculate the mass number of oxygen for all its isotopes.

Answer 1

Hint : Mass number describes the sum of protons and neutrons present in an atomic nucleus of the element. While atomic number describes the number of protons present in an atomic nucleus of the element. The atomic number of oxygen elements is 8.
Mass number is given by the following formula:
$A=Z+N----\left( 1 \right)$
Where A, Z and N refers to the mass number, atomic number and number of neutrons, respectively for a particular element.

Complete Step By Step Answer:
The element oxygen has three isotopes having the number of neutrons present in the nucleus are 8, 9 and 10. As we know that the atomic number of oxygen elements is 8. Put these values in equation (1), then we get
$A$ for the Ist isotope $=8+8$
$\Rightarrow$ $A$ for the Ist isotope $=16$ .
Now calculate $A$ for the 2nd isotope which has 9 neutrons.
$A$ for the 2nd isotope $=8+9$
$\Rightarrow$ $A$ for the 2nd isotope $=17$
At last, calculate $A$ for the 3rd isotope which has 9 neutrons.
$A$ for the 3rd isotope $=8+10$
$\Rightarrow$ $A$ for the 3rd isotope $=18$
Therefore, the mass number of oxygen for its three isotopes are 16, 17, and 18.

Additional Information:
Isotopes are the different forms of the same element which have the same atomic number but different mass number (or relative atomic mass). As a consequence, isotopes have different chemical properties.

Note :
It is important to note that oxygen has three isotopes having the number of neutrons present in the nucleus are 8, 9 and 10. Mass number describes the sum of protons and neutrons present in an atomic nucleus. The mass number of oxygen for its three isotopes are 16, 17, and 18.