What is the correct Lewis dot structure for MgCl2? 0 [Mg]2+ [:Cl:]– 0 :Cl: Mg :Cl: 0 [:Cl:]– [Mg]2+ [:Cl:]– 0 :Cl: – Mg – :Cl: 0 [Mg]+ [:Cl:]– [Mg]+ Question 6
The Correct Answer and Explanation is:
Of the choices provided, the correct Lewis dot structure for MgCl₂ is:
[:Cl:]⁻ [Mg]²⁺ [:Cl:]⁻
Explanation:
To determine the correct Lewis structure for magnesium chloride (MgCl₂), we must first identify the type of bonding that occurs between the magnesium and chlorine atoms.
- Identify the Elements and Bond Type:
- Magnesium (Mg) is an alkaline earth metal found in Group 2 of the periodic table. Metals have low electronegativity and tend to lose electrons to form positive ions (cations).
- Chlorine (Cl) is a halogen found in Group 17. Non-metals have high electronegativity and tend to gain electrons to form negative ions (anions).
- The bond between a metal and a non-metal is ionic, which involves the complete transfer of electrons from the metal to the non-metal, rather than the sharing of electrons seen in covalent bonds.
- Determine Valence Electrons and Ion Formation:
- A neutral magnesium atom has two valence electrons. To achieve a stable electron configuration like the noble gas Neon, it will lose these two electrons, forming a magnesium cation with a +2 charge (Mg²⁺).
- A neutral chlorine atom has seven valence electrons. To achieve a stable octet (a full outer shell of eight electrons) like the noble gas Argon, it needs to gain one electron. This forms a chloride anion with a -1 charge (Cl⁻).
- Construct the Compound:
- For the overall compound to be electrically neutral, the total positive charge must balance the total negative charge.
- One magnesium atom gives up two electrons. To accept these two electrons, two chlorine atoms are required, with each one gaining a single electron.
- This results in the formation of one Mg²⁺ ion and two Cl⁻ ions. The overall charge is (+2) + 2(-1) = 0.
- Draw the Lewis Structure for the Ionic Compound:
- For the cation (Mg²⁺), we write the element’s symbol inside brackets with the charge as a superscript. No dots are shown because it has lost its valence electrons.
- For the anions (Cl⁻), we write the element’s symbol with its complete octet (eight dots) inside brackets, with the charge as a superscript.
- The final structure must show all the resulting ions. Therefore, the correct Lewis structure for MgCl₂ shows one [Mg]²⁺ ion and two [:Cl:]⁻ ions.
The option [:Cl:]⁻ [Mg]²⁺ [:Cl:]⁻ correctly illustrates the two chloride anions, each with a full octet and a -1 charge, and the single magnesium cation with a +2 charge, accurately representing the ionic nature and stoichiometry of magnesium chloride
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