Explain with examples (1) Atomic number, (ii) Mass number, 8. (ii) Isotopes and iv) Isobars. Give any two uses of isotopes.
Answers
Answer and Explanation:
The atomic number of an element is defined as the number of protons present in it (or the number of electrons in a neutral atom). It is denoted as Z.
Example: if an element has 8 protons in its nucleus then the atomic number of that element will be 8. The element is Oxygen
The mass number is the sum of the number of protons and the number of neutrons. It is denoted as A.
Example: O has 8 protons and 8 neutrons, then A = 8+8 =16
Isotopes are atoms with the same number of protons but differ in the number of neutrons. They have the same atomic number but a different mass number.
Example: ¹⁶ O and ¹⁷O are isotopes of oxygen. Both has the same atomic number 8 but a different mass number.¹⁶O contains 8 neutrons whereas ¹⁷O contains 9 neutrons.
Isobars are the atoms of different elements with the same number of nucleons. They have a different atomic number but the same mass number.
Example: ²²Ne and ²²Na, ¹⁴N and ¹⁴C, ⁴⁰K and ⁴⁰Ca
Uses of isotopes :
- isotopic labeling to track reactions and metabolic pathway
- radioactive isotopes to treat or diagnose diseases