Answer:
When a calcium atom loses a single valence electron, the formed ion has an electronic configuration that is the same as a potassium atom (K). This configuration does not generate stability.
When a calcium atom loses its two valence electrons, the formed ion has an electronic configuration that is the same as an argon atom (Ar ), thus achieving stability.
Explanation:
Valencia electrons are the electrons found in the last electronic layer (called valence orbitals). These electrons are what determine the ability of the atom to form bonds. When an element joins another, it does so through its valence electrons.
The noble gases are placed in group 18 of the periodic table. The seven gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and oganeson (Og). These gases have a very low chemical reactivity, that is, little combination with other elements of the periodic table because they have eight valencia electrons. For that reason they are called inert gases.
The reactivity of an element measures the tendency to combine with others. In the formation of compounds there is a tendency to catch, lose or share electrons between atoms. The elements tend to react to resemble the closest noble gases in terms of their electronic configuration of the last layer (valencia electrons), that is, having eight electrons in the last layer to be stable. Then, the reactivity of an element measures the tendency to combine with others to generate the mentioned stability.
Calcium is in group 2 and period 4. Potassium is in group 1 and period 4. Given the above, when a calcium atom loses a single valence electron, the formed ion has an electronic configuration that is the same as a potassium atom (K). However, this configuration does not generate stability because a noble gas configuration was not reached. The nearest noble gas is Argon, located in group 18 and period 3. Then, when a calcium atom loses its two valence electrons, the formed ion has an electronic configuration that is the same as an argon atom (Ar ), thus achieving stability.
