Construct the Lewis structure model for the ionic compound potassium chloride using the following steps.
The Correct Answer and Explanation is:
Lewis Structure of Potassium Chloride (KCl)
Lewis Structure Model:
- Potassium (K) loses one electron to become K⁺.
- Chlorine (Cl) gains one electron to become Cl⁻.
- The result is an ionic bond between K⁺ and Cl⁻.
Lewis Dot Representation:
K• + •Cl: → K⁺ + [:Cl:]⁻
(with 8 valence electrons)
Explanation
Potassium chloride (KCl) is an ionic compound composed of potassium (K), a metal from Group 1 of the periodic table, and chlorine (Cl), a nonmetal from Group 17 (halogens). The formation of KCl involves the transfer of electrons rather than sharing, which is characteristic of covalent bonding.
Potassium has one valence electron in its outermost shell (4s¹). It tends to lose this electron to achieve a stable noble gas configuration, becoming a positively charged ion (K⁺) with an electron configuration similar to argon. Chlorine, on the other hand, has seven valence electrons (3s²3p⁵) and needs one more electron to complete its octet. When potassium donates its one electron to chlorine, chlorine becomes a negatively charged ion (Cl⁻), also achieving a noble gas configuration.
This electron transfer results in the formation of oppositely charged ions, K⁺ and Cl⁻, which are held together by electrostatic attraction, forming a stable ionic bond.
In a Lewis structure, we represent the ions with their charges:
- K⁺ has no dots around it, indicating the loss of its single valence electron.
- Cl⁻ is shown with eight dots (a complete octet), and a negative sign to show the gain of one electron.
This simple exchange and attraction between a metal and a nonmetal is a fundamental example of ionic bonding. The crystalline structure formed in the solid state contributes to the high melting point and electrical conductivity of KCl when dissolved in water or melted, making it a typical representative of ionic compounds.
Understanding this process helps in distinguishing between ionic and covalent compounds, as well as in predicting the properties and behavior of substances in various chemical reactions.
