Question

Give reasons for the following:

Isotopes occupy the same position in the periodic table.

Answer 1

• Isotopes- Atoms of an element having the same atomic number but a different mass number are known as isotopes.
• Atomic number(Z)- The total number of protons in the nucleus of an atom gives us the atomic number of that atom.
• Mass number(A)- The number of protons and neutrons combine to give us the mass number of an atom.
• Let us take an example of a Hydrogen atom.
• Hydrogen has three isotopes namely hydrogen, deuterium, and tritium.
• Hydrogen has 1 proton, Z=1, A=1.
• Deuterium has 1 proton and 1 neutron, Z=1, A=2.
• Tritium atom has 1 proton and 2 neutrons, Z=1, A=3.
• In these atoms atomic number is 1 while the mass number is changing.
• These atoms have the same atomic number which is the determining factor of their position in the periodic table.

Hence, isotopes occupy the same position in the periodic table since they have the same atomic number.