Covalent Bonding
Which statement correctly defines a covalent bond?
Explain, in terms of electrostatic forces, why a covalent bond holds two atoms together. Which statement provides the correct explanation?
How many shared pairs of electrons are present in a molecule of nitrogen, N₂?
A student draws a dot-and-cross diagram of water (H₂O) but forgets to include the lone pairs on oxygen. How many lone pairs should appear on the oxygen atom?
Oxygen forms a double bond in O₂ rather than a single bond. Which explanation is correct?
In ethane (CH₃CH₃), how many covalent bonds does each carbon atom form?
A mountaineer carries a portable gas stove to high altitude. The fuel is butane (C₄H₁₀), which boils at −1 °C, while the alternative fuel propane (C₃H₈) boils at −42 °C. Which explanation correctly accounts for the difference in boiling points?
Chlorine (Cl₂) is a gas at room temperature. Which explanation for this observation is correct?
A student writes: “Silicon dioxide has a low melting point because it contains covalent bonds.” Identify the error and select the correct statement.
Which statement correctly explains why diamond is extremely hard?
Graphite conducts electricity but diamond does not. Which explanation is correct?
Explain why graphite is soft and slippery. Which statement is correct?
C₆₀ fullerene has a much lower melting point than diamond. Which explanation is correct?
Methane (CH₄) does not conduct electricity. Which explanation is correct?
A student is given four unknown substances and told that one is graphite, one is diamond, one is solid iodine (I₂), and one is silicon dioxide (SiO₂). The student finds that only one substance conducts electricity. Which substance conducts, and why?
A molecule of ammonia (NH₃) has one lone pair on nitrogen, while a molecule of methane (CH₄) has no lone pairs on carbon. Which explanation correctly accounts for this difference?
An engineer needs a material that is very hard, does not conduct electricity, and has an extremely high melting point. Which material is most suitable?
Carbon dioxide (CO₂) contains two double bonds. Which statement correctly describes the bonding in CO₂?
Iodine (I₂) is a solid at room temperature, bromine (Br₂) is a liquid, and chlorine (Cl₂) is a gas. All three have simple molecular structures. Which factor is primarily responsible for this trend in physical states?
When comparing what happens during boiling of water and melting of silicon dioxide, which statement is correct?