Consider the elements and and their respective atomic numbers , and .
Which element is most reactive?
Electronic configuration:
1. The arrangement of electrons in the atomic orbitals of elements is characterized by electronic configuration.
2. The atomic numbers are filled in the K shell which can bear up to 2 electrons, the L shell which can bear up to 8 electrons and the M shell which can bear up to 18 electrons and so on.
3. The electronic configuration of Sodium , Magnesium and Aluminium can be obtained as:
4. As increase the valence electron, the reactivity of the element decreases. So in Sodium , Magnesium , and Aluminium ,
5. Sodium has the least number of valence electrons-1.
Hence, is most reactive among and .