Unit 5: Bonding Covalent & Intermolecular

Transcription

1 Name Unit 5: Bonding Covalent & Intermolecular Date Part 2 Questions 1. Ozone, O3 (g), is produced from oxygen, O2 (g) by electrical discharge during thunderstorms. The unbalanced equation below represents this reaction. A. Identify the type of bonding between the atoms in an oxygen molecule. B. How many pairs of electrons are shared between the oxygen atoms in O2? C. Explain, in terms of electron configuration, why an oxygen molecule is more stable than an oxygen atom. 2. Testing of an unknown solid shows that it has the properties listed below: Low melting point Nearly insoluble in water Poor conductor of electricity Relatively soft solid A. State the type of bonding that would be expected in the particles of this substance. B. Explain, in terms of particle attraction, why the solid has a low melting point. C. Explain why the particles of this substance are poor conductors of electricity.

2 3. In 1864, the Solvay process was developed to make soda ash. One step in the process is represented by the balanced equation below. NaCl + NH3 + CO2 + H2O NaHCO3 + NH4Cl A. Write the formula for one compound in the equation that contains both ionic and covalent bonds. B. Explain, in terms of electronegativity difference, why the bond between hydrogen and oxygen in a water molecule is more polar than the bond between hydrogen and nitrogen in an ammonia molecule. C. Draw an electron dot diagram for the reactant containing nitrogen. Identify its shape. 4. A. Draw an electron dot diagram for carbon tetrachloride, CCl4. B. Are the bonds in CCl4 polar or nonpolar? Explain. C. Is CCl4 a polar or nonpolar molecule? Explain. D. What is the shape of carbon tetrachloride?

3 5. A. Draw the structural formula for H2O. Include slight charges if present. B. Are the bonds in H2O polar or nonpolar? Explain. C. Is H2O a polar or nonpolar molecule? Explain. D. What is the shape of water? 6. The Lewis electron-dot diagrams for three substances are shown below. A. Describe, in terms of valence electrons, how the chemical bonds form in the substance represented in diagram 1. B. Describe, in terms of valence electrons, how the chemical bonds form in the substance represented in diagram 2. C. Determine the total number of electrons in the bonds between the nitrogen atom and the three hydrogen atoms represented in diagram 2. D. Explain, in terms of distribution of charge, why a molecule of the substance represented in diagram 3 is nonpolar.

4 E. Draw a Lewis electron-dot diagram for a molecule of Br2. Identify its bond polarity, molecular polarity, and shape. F. Identify the noble gas that has atoms with the same electron configuration as the positive ion represented in diagram At STP, Cl2 is a gas and I2 is a solid. When hydrogen reacts with chlorine, the compound hydrogen chloride is formed. When hydrogen reacts with iodine, the compound hydrogen iodide is formed. A. Determine the electronegativity difference for the bond in hydrogen chloride. B. Explain, in terms of intermolecular forces, why iodine is a solid at STP but chlorine is a gas at STP. C. Support your answer to part B in terms of the size of iodine and chlorine. 8. At standard pressure, water has unusual properties that are due to both its molecular structure and intermolecular forces. For example, although most liquids contract when they freeze, water expands, making ice less dense than liquid water. Water has a much higher boiling point than most other similar molecular compounds. A. Explain why H2O (s) floats on H2O ( ) when both are at 0 C. B. State the type of intermolecular force responsible for the unusual boiling point of H2O ( ) at standard pressure.

5 9. The table below shows the normal boiling point of four compounds. A. Draw a Lewis electron-dot diagram for a molecule of CH3Cl. B. Is CH3Cl a polar or nonpolar molecule? Explain in terms of charge distribution. C. Which compound has the strongest intermolecular forces? D. Identify the intermolecular forces present between molecules of HF ( ) and between molecules of HCl ( ). 10. Using the key, draw two water molecules in the box, showing the orientation of each water molecule toward the calcium ion.