Multiple Choice
Which of the following statements correctly describes the Lewis dot structure of the nitrate ion, NO3^-?
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11. Bonding & Molecular Structure
Lewis Dot Structures: Ions
Multiple Choice
Which of the following best describes the Lewis dot structure for the NH_2^- ion?
A
Nitrogen is bonded to three hydrogens, has one lone pair, and carries a negative charge.
B
Nitrogen is bonded to two hydrogens, has two lone pairs, and carries a negative charge.
C
Nitrogen is bonded to two hydrogens, has one lone pair, and carries a positive charge.
D
Nitrogen is bonded to two hydrogens, has no lone pairs, and carries a negative charge.
Verified step by step guidance1
Step 1: Determine the total number of valence electrons for the NH_2^- ion. Nitrogen has 5 valence electrons, each hydrogen has 1 valence electron, and the negative charge adds 1 extra electron. So, total valence electrons = 5 + (2 × 1) + 1.
Step 2: Draw the skeletal structure with nitrogen as the central atom bonded to two hydrogen atoms. Connect each hydrogen to nitrogen with a single bond, which uses 2 electrons per bond.
Step 3: Subtract the electrons used in bonding from the total valence electrons to find the remaining electrons to be placed as lone pairs.
Step 4: Place the remaining electrons as lone pairs on the nitrogen atom. Remember that nitrogen typically follows the octet rule, so it should have a total of 8 electrons around it (bonding + lone pairs).
Step 5: Assign the formal charge to nitrogen by using the formula: Formal charge = (Valence electrons of atom) - (Nonbonding electrons) - (Bonding electrons / 2). Confirm that the nitrogen carries the negative charge, consistent with the ion's overall charge.
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