Polarity and Intermolecular Forces
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C HAPTER
Chapter 1. Polarity and Intermolecular Forces
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Polarity and Intermolecular Forces
Worksheets Name _____________________ Class ______________________ Date ________________ Answer each of the questions below to show your achievement of the lesson objectives Lesson Objective: Describe how the electronegativity difference between two atoms in a covalent bond results in the formation of a nonpolar covalent, polar covalent, or ionic bond. 1. Electronegativity is the 1. 2. 3. 4.
number of positive charges on an ion relative ability of an atom to attract electrons ability of a cation to attract anions conductivity of a molecule
2. A non-polar covalent bond involves 1. 2. 3. 4.
equal sharing of electrons strong attraction of electrons by one atom balanced charge distribution in the bond unpaired electrons in orbitals
3. The Greek letter δ represents 1. 2. 3. 4.
change in state rate of reaction partial charge partial bond energy
4. The C-I bond is 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.
mostly ionic partially covalent polar covalent mostly covalent
True/False: A difference in electronegativity greater than 1.8 indicates a mainly ionic bond. True/False: The Si-Cl bond is mostly covalent True/False: The bond between Cl and Br is non-polar covalent. True/False: Bonds between a metal atom and a non-metal atom are usually ionic in nature. Define the following terms: a. non-covalent polar bond b. diatomic element c. polar covalent bond The atom with the highest electronegativity is ______. The atom with the lowest electronegativity is ______ . Arrange the following bonds in terms of increasing polarity, beginning with the lowest polarity: 1. Ni-P 1
www.ck12.org 2. 3. 4. 5.
Si-Cl Al-Cl Cu-Br Pb-I
Lesson Objective: Describe how molecular geometry plays a role in determining whether a molecule is polar or nonpolar 13. A polar molecule has 1. 2. 3. 4.
two negative poles two positive poles one end is slightly negative no charge distribution
14. A dipole has 1. 2. 3. 4. 15. 16. 17. 18.
two like charges two diffuse charges two poles two negative poles
True/False: Carbon tetrachloride is a non-polar molecule. True/False: The dipoles in the water molecule cancel each other out. Why is BF3 non-polar? What would be the effect on the polarity of the molecule formed when CCl4 has one Cl replaced by an H?
Lesson Objective: Distinguish between the following three types of intermolecular forces: dipole-dipole forces, London dispersion forces, and hydrogen bonds. 19. London dispersion forces 1. 2. 3. 4.
are seen between polar atoms are a result of differing electronegativities between two atoms are due to random motions of molecules are due to random motions of electrons
20. Hydrogen bonds involve 1. 2. 3. 4. 21. 22. 23. 24.
H covalently bonding to carbon H interacting with halogens H attached to an electronegative atom attracted to a lone pair of electrons H attached to an electronegative atom attracted to an electronegative atom
True/False: A H attached to a Si atom can form a hydrogen bond. True/False: Dispersion forces are a form of van der Waals interactions. ____________ ______________ are attractions between molecules. Why would London dispersion forces be so weak?
Lesson Objective: Describe how chemical bonding and intermolecular forces influence the properties of various compounds. 25. One of the statements below about water solubility of molecular compounds is not correct 1. molecules that form hydrogen bonds are usually soluble 2. molecules that form dispersion forces are usually soluble 3. molecules that form dipole-dipole forces are usually soluble 2
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Chapter 1. Polarity and Intermolecular Forces
4. molecules that form ions are usually soluble 26. When heated, diamond 1. 2. 3. 4.
melts at high temperature vaporizes to a gas does not change converts to graphite
27. 28. 29. 30. 31.
True/False: At room temperature, molecular compounds can be solid, liquid, or gas. True/False: HBr has a higher boiling point than HF. Melting and boiling points of molecular compounds are _____ in comparison with ionic compounds. Why are lone pair electrons needed to form H bonds? The degree to which a given bond is ionic or covalent is determined by calculating the difference in electronegativity between the two atoms involved in the bond. As an example, consider the bond that occurs between an atom of potassium and an atom of fluorine. Using the table, the difference in electronegativity is 4.0 − 0.8 = 3.2. Because the difference in electronegativity is relatively large, the bond between the two atoms is primarily ionic. Since the fluorine atom has a much larger attraction for electrons than the potassium atom does, the valence electron from the potassium atom is considered to have completely transferred to the fluorine atom. The figure below shows how the difference in electronegativity relates to the ionic or covalent character of a chemical bond. 32. Is there a clear difference between an ionic bond and a covalent bond? 33. Offer one reason why a knowledge of bond polarity might be useful in predicting chemical reactions.
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