1. Electronegativity Difference
* Calcium is a metal with a low electronegativity (tendency to attract electrons).
* Chlorine is a nonmetal with a high electronegativity.
* The large electronegativity difference between calcium and chlorine makes it favorable for them to form an ionic bond.
2. Octet Rule
* Calcium has 2 valence electrons (electrons in its outermost shell).
* Chlorine has 7 valence electrons.
* Calcium wants to lose its 2 valence electrons to achieve a stable octet (8 electrons in its outer shell).
* Each chlorine atom wants to gain 1 electron to achieve a stable octet.
3. Ionic Bonding
* To satisfy these needs, one calcium atom (Ca) loses its two valence electrons, becoming a positively charged calcium ion (Ca²⁺).
* These two electrons are transferred to two chlorine atoms, each becoming a negatively charged chloride ion (Cl⁻).
* The opposite charges of the ions attract each other, forming an ionic bond.
4. Formula Formation
* Since calcium loses two electrons and each chlorine atom gains one, you need two chlorine atoms to balance the charges.
* This leads to the formula CaCl₂.
In Summary
The combination of calcium and chlorine is driven by their electronegativity difference, the octet rule, and the formation of a stable ionic compound. The resulting compound, calcium chloride, has a stable structure where the charges are balanced, creating a neutral compound.
