Question

which of the highlighted chemical bonds in the molecules below is longest? shortest? in between? which highlighted bond requires the highest energy to break? lowest? in between? answer these questions by completing the second and third columns in the table.

Explanation:

Step1: Analyze bond length trends

Bond length increases down a group in the periodic table. Carbon (C), Silicon (Si), and Germanium (Ge) are in Group 14. As we go from C to Si to Ge, atomic radius increases. So, the \( H - Ge \) bond (in \( GeH_4 \)) is the longest, \( H - C \) bond (in \( CH_4 \)) is the shortest, and \( H - Si \) bond (in \( SiH_4 \)) is in - between.

Step2: Analyze bond - energy trends

Bond energy is inversely related to bond length (for similar types of bonds). Shorter bonds are stronger (higher bond energy). Since \( H - C \) bond is the shortest, it has the highest bond energy. \( H - Ge \) bond is the longest, so it has the lowest bond energy. And \( H - Si \) bond has an intermediate bond energy.

Answer:

Length of highlighted bond: \( H - Ge \) (longest), \( H - Si \) (in - between), \( H - C \) (shortest). Energy of highlighted bond: \( H - C \) (highest), \( H - Si \) (in - between), \( H - Ge \) (lowest).