Question

How do you list the alkaline earth metals in order of their chemical reactivity, starting with most reactive?

Answer 1

The atomic number of the atom of any element is the number of electrons present in that particular element in the atom of its most stable state. In the periodic table, the elements are arranged as per the number of electrons present in their orbitals. The number of electrons are also equal to the number of protons in that particular atom.

Complete answer:

The alkaline earth metals belong to group two in the periodic table. This means they have only two electrons in their orbital of the outermost shell. They are known to be reactive metals and thus readily form compounds. They are excellent reductants as well as they get oxidised very easily. Oxidation is the process of losing electrons and as they have only two electrons in their outermost shell, they can lose electrons very easily and thus get oxidised.
As we move down any group in the periodic table, the atomic number is known to increase. Alkaline earth metals are more reactive as their atomic number increases. So the more the atomic number, the more reactive the metal is. This is because as the atomic number increases, the number of orbitals increase and this causes the orbitals to move farther away from the nucleus which is at a fixed point at the middle of the atom.

Note: The elements of group two are beryllium, magnesium, calcium, strontium, barium and radium. They lose electrons to form positive cations. Cations are formed when the atom loses electrons and as we know that the number of protons is equal to electrons in a stable atom, thus when the atom loses electrons, a net positive charge is acquired by that atom.