General Chemistry: Intermolecular Forces of Solids and Liquids.pptx

Intermolecular Forces of Liquids and Solids

1. Intermolecular Forces and Liquids and Solids General Chemistry 2 By: Mr. Christian Nel R. Dominguez

2. Quick Check: Huh? Or Aha! Dipole-dipole interactions are stronger than hydrogen bonds. In liquids, the intermolecular forces are generally strong enough to keep the molecules in close contact but not in fixed positions. Ionic bonds are a type of intermolecular force that occurs in both solids and liquids. London dispersion forces are present in all molecules, regardless of whether they are polar or nonpolar. In a solid, the thermal energy of the molecules is typically greater than the energy of the intermolecular forces holding them together.

3. Quick Check: Huh? Or Aha! Dipole-dipole interactions are stronger than hydrogen bonds. Huh? In liquids, the intermolecular forces are generally strong enough to keep the molecules in close contact but not in fixed positions. Aha! Ionic bonds are a type of intermolecular force that occurs in both solids and liquids. Huh? London dispersion forces are present in all molecules, regardless of whether they are polar or nonpolar. Aha! In a solid, the thermal energy of the molecules is typically greater than the energy of the intermolecular forces holding them together. Huh?

4. Learning Goals By the end of the session, the learners should be able to: use the kinetic molecular model to explain the properties of solids and liquids; differentiate the types of intermolecular forces; describe some properties of liquids and the effect of intermolecular forces on them; explain the properties of water with its molecular structure and intermolecular force differentiate the structure of crystalline and amorphous solids; and show appreciation for the benefits of Chemistry to target SDG 12: Responsible Consumption and Production.

5. Kinetic Molecular Theory (KMT) The Kinetic Molecular Theory (KMT) is a model that explains the behavior of gases, and to some extent, liquids and solids, based on the idea that these substances are composed of small particles in constant, random motion. In 1738, Daniel Bernoulli published a model that contains the basic framework for the modern Kinetic Molecular theory

6. Solids vs Liquids

7. Activity 1.1: Main Idea Completion Intermolecular Forces (IMF) IMF Type Strength Description Example London Dispersion Forces Dipole-Dipole Interactions Hydrogen Bonding Ion-Dipole Interactions Ion-Ion Interactions

8. Intermolecular Forces Intermolecular forces are forces of attraction or repulsion which act between neighboring particles (atoms, molecules or ions) They are weak compared to the intramolecular forces , which keep a molecule together (e.g., covalent and ionic bonding).

9. London Dispersion Forces London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. For example, Fluorine (F2), Chlorine (Cl2), Oxygen (O2), and Neon (Ne)

10. Dipole-Dipole Forces Dipole-dipole forces are attractive forces between the positive end of one polar molecule and the negative end of another polar molecule. For example, Hydrogen chloride (HCl) , hydrogen fluoride (HF ), and water (H2O).

11. Hydrogen Bonding Hydrogen bonding is a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. For example, Water (H₂O), Ethanol (C₂H₅OH), and Ammonia (NH₃)

12. Ion – Dipole Forces An ion-dipole force is an attractive force that results from the electrostatic attraction between an ion and a neutral molecule that has a dipole. For example, sodium (Na+) and chlorine (Cl–) and a polar water molecule (H2O

13. Ion-Ion Forces An ion-ion force is an attractive force between ions with opposite charges known as ionic bonds. For example, electrostatic attraction between the magnesium ion (Mg²⁺) and the oxide ion (O²⁻) in magnesium oxide.

14. Activity 1: Main Idea Completion Intermolecular Forces (IMF) IMF Type Strength Description Example London Dispersion Forces Temporary dipoles Weak Caused by random movement of electrons. O₂, N₂ (nonpolar gases) Dipole-Dipole Interactions Attraction between polar molecules Moderate Attraction between positive and negative ends of polar molecules. HCl, H₂S (polar molecules) Hydrogen Bonding Special dipole-dipole Stronger Strong attraction between H and N, O, or F. Water (H₂O), Ammonia (NH₃) Ion-Dipole Interactions Ion and polar molecule Very Strong Attraction between ions and polar molecules. NaCl in water Ion-Ion Interactions Attraction between ions Strongest Attraction between positive and negative ions. MgO (salt crystals)

15. Practice Exercise What type of force will act in the following substances/solution? Justify your answer. Potassium chloride ( KCl ) dissolved in water Carbon dioxide (CO2) Ammonia (NH3)

16. Practice Exercise What type of force will act in the following substances/solution? Justify your answer. Potassium chloride ( KCl ) dissolved in water – Ion-Dipole force Carbon dioxide (CO2) – London dispersion forces Ammonia (NH3) – Hydrogen bond

17. Activity 1.2: Main Idea Completion General Properties of Liquids Property Effect of Stronger IMFs Example Boiling Point Surface Tension Viscosity Vapor Pressure Heat of Vaporization

18. Boiling Point The boiling point of a pure substance is the temperature at which the substance transitions from a liquid to the gaseous phase. The stronger the IMFs, the higher the boiling point..

19. Surface Tension Surface tension is the energy required to increase the surface area of a liquid by a given amount. The stronger the intermolecular interactions, the greater the surface tension.

20. Viscosity Viscosity is a measure of a fluid's resistance to flow . It is determined by the strength of intermolecular forces between the fluid's molecules. The stronger the intermolecular forces, the higher the viscosity.

21. Vapor Pressure The vapor pressure exerted by the vapor in equilibrium with a liquid in a closed container at a given temperature. The stronger these forces, the lower the rate of evaporation and the lower the vapor pressure.

22. Heat of Vaporization The Heat of Vaporization is the quantity of heat that needs to be absorbed to vaporize a particular quantity of liquid at a constant temperature. The stronger the intermolecular forces, the higher the heat of vaporization.

23. Activity 1.2: Main Idea Completion General Properties of Liquids Property Effect of Stronger IMFs Example Boiling Point Higher IMFs increase the boiling point Water (100°C) vs. Methane (-161°C) Surface Tension Stronger IMFs increase surface tension. Water vs. Alcohol Viscosity Stronger IMFs increase viscosity (slower flow) Honey vs. Water Vapor Pressure Higher IMFs, lower vapor pressure (escapes easily) Water vs. Ether Heat of Vaporization Higher IMFs increase the energy to vaporize. Water (40.7 kJ/mol) vs. Ethane (5.5 kJ/mol)

24. Quick Check: Thumbs Up or Thumbs Down Surface tension is primarily influenced by intermolecular forces (IMF) between molecules in a liquid. Boiling point is affected by intermolecular forces, and liquids with stronger IMF generally have lower boiling points. Viscosity is a measure of a liquid's resistance to flow, and it is generally higher in liquids with stronger intermolecular forces.

25. Quick Check: Thumbs Up or Thumbs Down Surface tension is primarily influenced by intermolecular forces (IMF) between molecules in a liquid. *True Boiling point is affected by intermolecular forces, and liquids with stronger IMF generally have lower boiling points. *False Viscosity is a measure of a liquid's resistance to flow, and it is generally higher in liquids with stronger IMF. *True

26. Activity 2: T-Chart Completion General Properties of Liquids Property Effect of Stronger IMFs Example Boiling Point Higher IMFs increase the boiling point Water (100°C) vs. Methane (-161°C) Surface Tension Stronger IMFs increase surface tension. Water vs. Alcohol Viscosity Stronger IMFs increase viscosity (slower flow) Honey vs. Water Vapor Pressure Higher IMFs, lower vapor pressure (escapes easily) Water vs. Ether Heat of Vaporization Higher IMFs increase the energy to vaporize. Water (40.7 kJ/mol) vs. Ethane (5.5 kJ/mol)

27. Types and Properties of Solids The intermolecular/interatomic force of attraction is maximum in solids. Due to this, the molecules of solids are closely packed. Based on the arrangement of constituent particles, solids are classified into two-state types: Crystalline Solids and Amorphous Solids.

28. Amorphous Solids Amorphous solid , any noncrystalline solid in which the atoms and molecu les are not organized in a definite lattice pattern For example: glass, plastic, and gel.

29. Crystalline Solids A crystalline solid or crystal consists of a highly regular pattern of atoms or molecules, forming a crystal lattice from a small repeating pattern called unit cell. For example: diamonds, table salt, ice, sugar, and most metals.

30. Classifications of Crystalline Solids Group 8A Covalent bonds Low melting and boiling point Noble gases

31. Importance of Chemistry How will you exhibit responsible consumption and production upon learning the intermolecular forces of solids and liquids?

32. Lesson Summary Intermolecular forces, often abbreviated to IMF, are the attractive and repulsive forces that arise between the molecules of a substance. There are four types of intermolecular forces: dipole-dipole, ion-dipole, London dispersion, and hydrogen bonding. The properties of liquids affected by IMF are surface tension, viscosity, vapor pressure, boiling point, and heat of vaporization. Crystalline solids have an ordered, regular structure, while amorphous solids do not. The classifications of crystalline solids are ionic, molecular, metallic, network, and Group 8A.