Calcium is in Group 2, so each calcium atom loses two electrons from its outer shell. This forms a positive calcium ion with a 2+ charge (Ca²⁺).
Chlorine is in Group 7, so each chlorine atom needs to gain one electron to get a full outer shell.
Two chlorine atoms each gain one electron. This forms two negative chloride ions, each with a 1- charge (Cl⁻). The electrons are transferred from the calcium atom to the chlorine atoms.
Ionic bonding involves the transfer of electrons from a metal to a non-metal.
1. **Calcium (Ca):** Calcium is in Group 2 of the periodic table. Its atoms have two electrons in their outer shell. To achieve a stable, full outer shell, each calcium atom loses these two electrons. When it loses two negative electrons, it becomes a positive ion with a charge of 2+, written as Ca²⁺.
2. **Chlorine (Cl):** Chlorine is in Group 7. Its atoms have seven electrons in their outer shell. To achieve a stable, full outer shell, each chlorine atom needs to gain one electron. When it gains one negative electron, it becomes a negative ion with a charge of 1-, written as Cl⁻.
3. **Formation of Calcium Chloride (CaCl₂):** One calcium atom transfers its two outer electrons to two separate chlorine atoms (one electron to each). This results in the formation of one Ca²⁺ ion and two Cl⁻ ions. The strong electrostatic attraction between these oppositely charged ions forms the ionic bond.
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