Multiple Choice
Which of the following is the correct number of valence electrons for the ion SnF6^{2-}, and which Lewis structure best represents it?
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11. Bonding & Molecular Structure
Lewis Dot Structures: Ions
Multiple Choice
Which of the following statements correctly describes the Lewis dot structure for the ionic compound Ca3N2?
A
Each Ca atom loses two electrons to form Ca2+ ions, and each N atom gains three electrons to form N3− ions.
B
Each Ca atom loses one electron to form Ca+ ions, and each N atom gains two electrons to form N2− ions.
C
Each Ca atom loses two electrons to form Ca2+ ions, and each N atom gains three electrons to form N3− ions. The Lewis structure shows Ca2+ ions without dots and N3− ions surrounded by eight dots.
D
The Lewis structure shows Ca atoms with six valence electrons and N atoms with five valence electrons.
Verified step by step guidance1
Identify the elements involved in the compound Ca3N2: calcium (Ca) and nitrogen (N).
Determine the typical charges of ions formed by these elements based on their positions in the periodic table: calcium, an alkaline earth metal, typically loses 2 electrons to form Ca^{2+}, and nitrogen, a nonmetal in group 15, typically gains 3 electrons to form N^{3-}.
Use the formula Ca3N2 to check charge balance: 3 Ca^{2+} ions contribute a total charge of +6, and 2 N^{3-} ions contribute a total charge of -6, which balances to zero, confirming the ionic formula is correct.
Understand the Lewis dot structure representation for ionic compounds: metal cations (Ca^{2+}) are shown without dots because they have lost their valence electrons, while nonmetal anions (N^{3-}) are shown with a full octet of dots (8 valence electrons) to represent the gained electrons.
Conclude that the correct Lewis structure for Ca3N2 shows Ca^{2+} ions without dots and N^{3-} ions surrounded by eight dots, reflecting the transfer of electrons and the formation of ions.
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