CHEMISTRY · Multi-part · AP · Chemistry · Compound Structure and Properties · Compound Structure and Properties
Problem
Ammonium nitrate, NH₄NO₃, is a common component of fertilizer. For safety documentation, a chemist must present clear particulate-level drawings of each polyatomic ion it contains.
Complete the tasks below. Whenever you are asked to draw a structure, enclose the ion in brackets and show the charge outside the brackets.
(a) Identify the two polyatomic ions present in NH₄NO₃ and state the overall charge of each.
(b) For each ion identified in part (a), calculate the total number of valence electrons that must be depicted in a correct Lewis structure.
(c) Draw all valid resonance structures for the nitrate ion. Assign formal charges on every atom in each structure.
(d) Using the resonance set from part (c), determine the average N–O bond order in nitrate and explain how this value accounts for experimentally observed equivalence of the three N–O bond lengths.
(e) The ammonium ion has no resonance structures. Explain, using formal charge considerations and electron count, why resonance is unnecessary for a complete Lewis representation of NH₄⁺.