Lewis structures can be used to understand why some molecules react in certain ways. Write the Lewis structures for the reactants and products in the reactions described below. a. Nitrogen dioxide dimerizes to produce dinitrogen tetroxide. b. Boron trihydride accepts a pair of electrons from ammonia, forming \(\mathrm{BH}_{3} \mathrm{NH}_{3}\). Give a possible explanation for why these two reactions occur.

For the given reactions: a. Nitrogen dioxide (NO₂) dimerizes to produce dinitrogen tetroxide (N₂O₄). b. Boron trihydride (BH₃) reacts with ammonia (NH₃) to form the adduct \(\mathrm{BH}_{3} \mathrm{NH}_{3}\).

For reaction a: - Nitrogen dioxide (NO₂): Lewis structure contains a nitrogen atom with a single unpaired electron, double bonded to one oxygen atom and single bonded to the other oxygen atom, which bears a formal negative charge. - Dinitrogen tetroxide (N₂O₄): Lewis structure contains two nitrogen atoms, each double bonded to two oxygen atoms. For reaction b: - Boron trihydride (BH₃): Lewis structure contains a boron atom with three single bonds to three hydrogen atoms. - Ammonia (NH₃): Lewis structure contains a nitrogen atom with a lone pair of electrons and three single bonds to three hydrogen atoms.

a. The dimerization of NO₂ to form N₂O₄ occurs because it allows nitrogen atoms to attain a full octet. In NO₂, the nitrogen atom has an unpaired electron, which makes it a radical. The dimerization reaction results in the sharing of this unpaired electron, forming a N-N single bond and enabling both nitrogen atoms to achieve a full octet. b. The reaction of BH₃ with NH₃ to form BH₃NH₃ occurs due to the electron-deficient boron atom in BH₃ and the electron-rich nitrogen atom in NH₃. Boron in BH₃ has only six valence electrons, which does not satisfy the octet rule. The nitrogen atom in NH₃, with a lone pair of electrons, can form a dative covalent (coordinate) bond by donating its electron pair into the empty orbital of boron. This results in the formation of the adduct BH₃NH₃, wherein both boron and nitrogen atoms attain a full octet configuration.