Barium azide is 62.04 % Ba and 37.96 % N. Each azide ion has...

Barium azide is $62.04 \%$ Ba and $37.96 \%$ N. Each azide ion has a net charge of $1-$. (a) Determine the chemical formula of the azide ion. (b) Write three resonance structures for the azide ion. (c) Which structure is most important? (d) Predict the bond lengths in the ion.

Key Concepts

Stoichiometry and Molecular Formula

This concept involves using percent composition data to determine the ratios of elements in a compound. By relating the given mass percentages to their atomic masses, one can deduce the simplest whole-number ratio of atoms in the compound, which in turn leads to the correct molecular formula.

Resonance Structures

Resonance is a fundamental idea in chemistry where a single molecule or ion is best represented by two or more valid Lewis structures. These structures show the delocalization of electrons, especially in systems with conjugated double bonds or charges that are spread over several atoms, making the actual molecule a hybrid of the contributing structures.

Resonance Contribution and Stability

In a resonance hybrid, not all contributing structures typically have equal weight. The contributing form that minimizes formal charges, obeys the octet rule, and places negative charges on more electronegative atoms is usually the most significant. This concept is critical when assessing which resonance structure most accurately represents the electron distribution in a molecule.

Bond Order and Bond Length Prediction

The idea of bond order reflects the number of chemical bonds between a pair of atoms, influencing bond energy and bond length. In species where resonance leads to electron delocalization, the bond lengths are intermediate between those expected for a single bond and a double bond. This concept helps predict variations in bond lengths within a molecule based on its resonance hybrid structure.