Covalent bonding：練習題

How is a covalent bond typically formed between atoms?

Oxygen (\(O_2\)) is a simple molecular substance. Which statement correctly explains why it is a gas at room temperature?

Diamond (giant covalent structure) and water (simple molecular structure) both consist only of atoms joined by strong covalent bonds. Which statement correctly compares their properties?

Which of the following statements provides the best description of a covalent bond?

Ammonia, \(NH_3\), is formed when nitrogen (Group 5) and hydrogen (Group 1) bond covalently. How many non-bonding (lone) pairs of electrons are present on the central nitrogen atom in a molecule of ammonia?

A covalent bond is the electrostatic attraction between which two types of particles?

Explain why simple molecular substances, such as iodine or sulfur, typically have low melting and boiling points.

Explain why hydrogen chloride (\(HCl\)) has a very low boiling point compared to diamond, making specific reference to the types of forces or bonds that are overcome during boiling in each substance.

Diamond and graphite are both allotropes of carbon with giant covalent structures, while Buckminsterfullerene (\(C_{60}\)) has a simple molecular structure.

(a) Explain, in terms of its structure and bonding, why graphite can conduct electricity but diamond cannot. (3 points)

(b) Explain why diamond has a much higher melting point than Buckminsterfullerene. In your answer, refer to the types of forces or bonds that are broken during melting for each substance. (3 points)

(c) Using your knowledge of covalent bonding, explain why the melting point of ethane (\(C_2H_6\)) is lower than that of hexane (\(C_6H_{14}\)). (2 points)