Question

Chlorine is an element of atomic number 17. It is a mixture of two isotopes having mass number of 35 and 37.

Explain why the two atoms ${{}^{35}\mathrm{Cl}}_{17}$,${{}^{37}\mathrm{Cl}}_{17}$have the same chemical reactions.

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.
• In the given two isotopes we have-

Isotope	Number of electrons	Number of protons	Number of neutrons
${{}^{35}\mathrm{Cl}}_{17}$	17	17	18
${{}^{37}\mathrm{Cl}}_{17}$	17	17	20

• Here it is evident that the number of protons is the same in both atoms.
• Chemical properties of an element are dependent on the number of protons.

Since both isotopes have the same number of protons so they have the same chemical reactions.