Question

Elements A and B have mass numbers 18 and 16 respectively. Which of these is more reactive and why?

Answer 1

Reactivity is decided on the basis of number of electrons for which atomic number should be given. However on the basis of mass number the elemnent seems to be oxygen and fluorine .
Out of these two fluorine is more reactive as it has 7 valence electron and it tries to accept electron readily to acquire nobel gas configuration. It has very high electronegativity value.