化學鍵與結構：练习题

According to the Electron-Pair Repulsion Theory, what is the shape of a boron trichloride, \( \text{BCl}_3 \), molecule?

Which of the following molecules contains polar bonds but is a non-polar molecule overall?

According to the Valence Shell Electron Pair Repulsion (VSEPR) theory, what are the shape and bond angles of a \(\text{PCl}_5\) molecule in the gas phase?

Which of the following substances has a simple molecular structure with London forces between its molecules?

Which of the following molecules has a linear shape and a bond angle of \( 180^\circ \)?

Describe the metallic bonding in a magnesium lattice in terms of particles and the nature of the attraction between them.

Using the electron-pair repulsion theory, predict the molecular shape and the \( \text{Cl-I-Cl} \) bond angle in the tetrachloroiodate(III) ion, \( \text{ICl}_4^- \). Justify your prediction by stating the number of bonding and lone pairs of electrons around the central iodine atom.

Explain, in terms of the properties of the cations, why magnesium iodide, \( \text{MgI}_2 \), exhibits a greater degree of covalent character than sodium iodide, \( \text{NaI} \).

Ammonia, \( NH_{3} \), and boron trifluoride, \( BF_{3} \), are molecules with different shapes.

(a) Draw a dot-and-cross diagram for a molecule of ammonia, showing only the outer shell electrons.
(b) State the shape and the bond angle of the ammonia molecule.
(c) Explain why the bond angle in ammonia is less than the bond angle in a tetrahedral molecule like methane, \( CH_{4} \), using electron-pair repulsion theory.

This question is about ionic and metallic bonding.

(a) Magnesium oxide, \( \text{MgO} \), and sodium chloride, \( \text{NaCl} \), both have giant ionic lattices. Explain why the melting temperature of magnesium oxide is much higher than that of sodium chloride.
(b) Describe metallic bonding in terms of the particles involved and the forces between them.
(c) Explain why metals are good conductors of electricity.