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Intermolecular forces summary

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Aly Barakat
Aly Barakat

This document defines key terms related to intermolecular forces and phase changes of matter. It defines terms like intramolecular forces, intermolecular forces, dipole-dipole interaction, hydrogen bonding, surface tension, viscosity, cohesion, adhesion, unit cell, molar heat of vaporization, molar heat of fusion, critical temperature, critical pressure, and more. It also provides explanations and relationships between these various terms.

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Chapter 11 SUMMARY Ali Barakat ali
Word Definition By: Ali Barakat CHAPTER 11 Phase A homogeneous part of the system in contact with other parts of the system but separated from them by a well-defined boundary. Dipole-dipole interaction Attractive forces between polar molecules (molecules that poses dipole moment). H-bonding A strong type of dipole-dipole interaction, formed between hydrogen atom in a polar molecule and a high-electronegative atom in another polar molecule (N, O, F). INTRAMOLECULAR FORCES Attractive forces that holds the atoms together within a molecule. INTERMOLECULAR FORCES Attractive forces between molecules. Surface tension The amount of energy required to stretch or increase the surface of a liquid by a unit area.(J/m2) Viscosity A measure of a fluid’s resistance to flow. Cohesion The intermolecular attraction between like molecules. Adhesion The intermolecular attraction between unlike molecules. Unit cell The basic repeating structural unit of a crystalline solid.
Molar heat of vaporization The energy required to vaporize 1 mole of a liquid at its boiling point. Molar heat of fusion The energy required to melt 1 mole of a solid substance at its freezing point. Critical temperature The temperature above which the gas cannot be made to liquefy, no matter how great the applied pressure Critical pressure the minimum pressure that must be applied to bring about liquefaction at the critical temperature Surfactant A substance added to liquid which decreases its surface tension. By: Ali Barakat
By: Ali Barakat Highlights INTRAMOLECULAR FORCES Attractive forces that holds the atoms together within a molecule. Stabilize individual molecules. Stronger. INTERMOLECULAR FORCES Attractive forces between molecules. Responsible for the bulk properties of the matter.  Boiling point.  Freezing point.  DHvap  DHfus  DHsub Weaker. ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
By: Ali Barakat
Nucleus & Inner shell e - CROSS SECTION OF METALLIC CRYSTALLE By: Ali Barakat
By: Ali Barakat
By: Ali Barakat T2 > T1 At the higher temperature the curve flattens out. The higher the temperature, the greater the number of molecules with high kinetic energy.
1. The strength of ion-dipole force depends on: Charge and size of the ion. Size and magnitude of the dipole moment of the polar molecule. 2. Charges of cations are usually more concentrated than anions that have the same magnitude. Because cations are usually smaller than anions. 3. Mg2+ interacts more strongly with H2O molecules than Na2+. Because Mg2+ has a higher charge than Na+. Because Mg2+ has a smaller ionic radius than Na+. Heat of hydration of Mg2+ is greater than heat of hydration of Na+. 4. If we placed an ion or a polar molecule near an atom or a nonpolar molecule, the electron distribution of the atom (or the molecule) will be distorted by the force exerted by the ion or the polar molecule resulting in a kind of dipole called induced dipole Because the separation of positive and negative ions in the atom or the nonpolar molecule is due to the proximity of an ion or a polar molecule. 5. Polarizability The ease with which the electron distribution in the atom or molecule can be distorted. 6. As electrons are in continuous motion, a nonpolar molecule could have an instantaneous dipole. By: Ali Barakat
7. The likelihood of a dipole moment being induced depends on:- Charge of the ion OR the strength of the dipole. The polarizability of the atom or the nonpolar molecule. 8. Polarizability increases with:- Greater number of electrons. More diffuse electron cloud. 9. Dispersion force ∝ polarizability ∝ Molar mass (GR???)  Molecules with larger molar mass tend to have more electrons and dispersion forces increase in strength by increasing number of electrons.  Larger molar mass means a bigger atom whose electron distribution is more easily distributed because the outer electrons are less tightly held to the nuclei. Dispersion force ∝ Low Temperature Dispersion force ∝ reduced atomic speed 10. Melting point increases while Molar Mass is increasing. 11. At any moment, the atom could have a dipole moment created by the specific positions of its electron, and it is called instantaneous dipole because it lasts for just a tiny fraction of second. 12. Instantaneous dipoles cancel each other. 13. Dispersion force: attractive forces that arise as a result of temporary dipoles induced in atoms and nonpolar molecules. 14. Surface tension ∝ I.M.F By: Ali Barakat
15. Polarizability enables gases containing atoms or nonpolar molecules to condense. 16. Cohesion > Adhesion (Mercury)……. Convex meniscus 17. Adhesion > Cohesion (Water)……….. Concave meniscus 18. Surfactant - substance added to liquid which decreases the surface tension. 19. Viscosity ∝ low temperature ∝ M.M ∝ density ∝ I.M.F 20. Viscosity Units: J/m2 --------- N.s/m2……………….. Kg/(m.s) 21. Surface tension results from the net inward force experienced by the molecules on the surface of a liquid. 22. Water has maximum density at 40C. 23. In f.c.c √ ……. √ ..…. By: Ali Barakat √ .…. ….. √ √ 24. In b.c.c √ √ √ √
25. In s.c.c 26. The equilibrium vapor pressure is the vapor pressure measured when a dynamic equilibrium exists between condensation and evaporation. 27. A state of dynamic equilibrium, in which the rate of a forward process is exactly balanced by the rate of reverse process. 28. Molar heat of vaporization (DHvap): is the energy required to vaporize 1 mole of a liquid at its boiling point. 29. Clausius-Clapeyron Equation By: Ali Barakat ( ). 30. Boiling point: the temperature at which the (equilibrium) vapor pressure of a liquid is equal to the external pressure. 31. Normal boiling point: the temperature at which a liquid boils when the external pressure is 1 atm. 32. Critical temperature (Tc): the maximum temperature at which the gas can be made to liquefy, with no effect for raising the pressure at any temperature above the critical temperature.
33. The critical pressure (Pc): the minimum pressure that must be applied to bring about liquefaction at the critical temperature. 34. The melting point of a solid or the freezing point of a liquid is the temperature at which the solid and liquid phases coexist in equilibrium. 35. Molar heat of fusion (DHfus): the energy required to melt 1 mole of a solid substance at its freezing point. 36. Molar heat of sublimation (DHsub): the energy required to sublime 1 mole of a solid. 37. Due to Hess’s Law: DHsub = DHfus + DHvap 38. A phase diagram summarizes the conditions at which a substance exists as a solid, liquid, or gas. 39. An increase in the pressure causes the boiling point to increase and melting point to decrease. Because, ∝ And so an increase in the pressure of ice favors the liquid phase. 40. By: Ali Barakat …………………………… Z:

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Intermolecular forces summary

  • 1. Chapter 11 SUMMARY Ali Barakat ali
  • 2. Word Definition By: Ali Barakat CHAPTER 11 Phase A homogeneous part of the system in contact with other parts of the system but separated from them by a well-defined boundary. Dipole-dipole interaction Attractive forces between polar molecules (molecules that poses dipole moment). H-bonding A strong type of dipole-dipole interaction, formed between hydrogen atom in a polar molecule and a high-electronegative atom in another polar molecule (N, O, F). INTRAMOLECULAR FORCES Attractive forces that holds the atoms together within a molecule. INTERMOLECULAR FORCES Attractive forces between molecules. Surface tension The amount of energy required to stretch or increase the surface of a liquid by a unit area.(J/m2) Viscosity A measure of a fluid’s resistance to flow. Cohesion The intermolecular attraction between like molecules. Adhesion The intermolecular attraction between unlike molecules. Unit cell The basic repeating structural unit of a crystalline solid.
  • 3. Molar heat of vaporization The energy required to vaporize 1 mole of a liquid at its boiling point. Molar heat of fusion The energy required to melt 1 mole of a solid substance at its freezing point. Critical temperature The temperature above which the gas cannot be made to liquefy, no matter how great the applied pressure Critical pressure the minimum pressure that must be applied to bring about liquefaction at the critical temperature Surfactant A substance added to liquid which decreases its surface tension. By: Ali Barakat
  • 4. By: Ali Barakat Highlights INTRAMOLECULAR FORCES Attractive forces that holds the atoms together within a molecule. Stabilize individual molecules. Stronger. INTERMOLECULAR FORCES Attractive forces between molecules. Responsible for the bulk properties of the matter.  Boiling point.  Freezing point.  DHvap  DHfus  DHsub Weaker. ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
  • 6. Nucleus & Inner shell e - CROSS SECTION OF METALLIC CRYSTALLE By: Ali Barakat
  • 8. By: Ali Barakat T2 > T1 At the higher temperature the curve flattens out. The higher the temperature, the greater the number of molecules with high kinetic energy.
  • 9. 1. The strength of ion-dipole force depends on: Charge and size of the ion. Size and magnitude of the dipole moment of the polar molecule. 2. Charges of cations are usually more concentrated than anions that have the same magnitude. Because cations are usually smaller than anions. 3. Mg2+ interacts more strongly with H2O molecules than Na2+. Because Mg2+ has a higher charge than Na+. Because Mg2+ has a smaller ionic radius than Na+. Heat of hydration of Mg2+ is greater than heat of hydration of Na+. 4. If we placed an ion or a polar molecule near an atom or a nonpolar molecule, the electron distribution of the atom (or the molecule) will be distorted by the force exerted by the ion or the polar molecule resulting in a kind of dipole called induced dipole Because the separation of positive and negative ions in the atom or the nonpolar molecule is due to the proximity of an ion or a polar molecule. 5. Polarizability The ease with which the electron distribution in the atom or molecule can be distorted. 6. As electrons are in continuous motion, a nonpolar molecule could have an instantaneous dipole. By: Ali Barakat
  • 10. 7. The likelihood of a dipole moment being induced depends on:- Charge of the ion OR the strength of the dipole. The polarizability of the atom or the nonpolar molecule. 8. Polarizability increases with:- Greater number of electrons. More diffuse electron cloud. 9. Dispersion force ∝ polarizability ∝ Molar mass (GR???)  Molecules with larger molar mass tend to have more electrons and dispersion forces increase in strength by increasing number of electrons.  Larger molar mass means a bigger atom whose electron distribution is more easily distributed because the outer electrons are less tightly held to the nuclei. Dispersion force ∝ Low Temperature Dispersion force ∝ reduced atomic speed 10. Melting point increases while Molar Mass is increasing. 11. At any moment, the atom could have a dipole moment created by the specific positions of its electron, and it is called instantaneous dipole because it lasts for just a tiny fraction of second. 12. Instantaneous dipoles cancel each other. 13. Dispersion force: attractive forces that arise as a result of temporary dipoles induced in atoms and nonpolar molecules. 14. Surface tension ∝ I.M.F By: Ali Barakat
  • 11. 15. Polarizability enables gases containing atoms or nonpolar molecules to condense. 16. Cohesion > Adhesion (Mercury)……. Convex meniscus 17. Adhesion > Cohesion (Water)……….. Concave meniscus 18. Surfactant - substance added to liquid which decreases the surface tension. 19. Viscosity ∝ low temperature ∝ M.M ∝ density ∝ I.M.F 20. Viscosity Units: J/m2 --------- N.s/m2……………….. Kg/(m.s) 21. Surface tension results from the net inward force experienced by the molecules on the surface of a liquid. 22. Water has maximum density at 40C. 23. In f.c.c √ ……. √ ..…. By: Ali Barakat √ .…. ….. √ √ 24. In b.c.c √ √ √ √
  • 12. 25. In s.c.c 26. The equilibrium vapor pressure is the vapor pressure measured when a dynamic equilibrium exists between condensation and evaporation. 27. A state of dynamic equilibrium, in which the rate of a forward process is exactly balanced by the rate of reverse process. 28. Molar heat of vaporization (DHvap): is the energy required to vaporize 1 mole of a liquid at its boiling point. 29. Clausius-Clapeyron Equation By: Ali Barakat ( ). 30. Boiling point: the temperature at which the (equilibrium) vapor pressure of a liquid is equal to the external pressure. 31. Normal boiling point: the temperature at which a liquid boils when the external pressure is 1 atm. 32. Critical temperature (Tc): the maximum temperature at which the gas can be made to liquefy, with no effect for raising the pressure at any temperature above the critical temperature.
  • 13. 33. The critical pressure (Pc): the minimum pressure that must be applied to bring about liquefaction at the critical temperature. 34. The melting point of a solid or the freezing point of a liquid is the temperature at which the solid and liquid phases coexist in equilibrium. 35. Molar heat of fusion (DHfus): the energy required to melt 1 mole of a solid substance at its freezing point. 36. Molar heat of sublimation (DHsub): the energy required to sublime 1 mole of a solid. 37. Due to Hess’s Law: DHsub = DHfus + DHvap 38. A phase diagram summarizes the conditions at which a substance exists as a solid, liquid, or gas. 39. An increase in the pressure causes the boiling point to increase and melting point to decrease. Because, ∝ And so an increase in the pressure of ice favors the liquid phase. 40. By: Ali Barakat …………………………… Z: