chem week1 inter/intra molecular forces

• Kinetic Molecular Theory states that the particles of liquids have kinetic energy that overcomes their attractive forces, allowing them to move short distances and flow
• Solids, liquids, and gases exist as different states of matter with varying attractive forces between particles
• Solids have the strongest forces of attraction among the three states of matter
• Particles in solids and liquids are significantly attracted to each other and are close together, occupying a significant volume of the substance
• Liquids are made up of particles that are close to each other and have kinetic energy, allowing them to move but only in short distances before colliding with each other
• Liquids have moderately high density, low compressibility, and thermal expansion
• Most liquids exist as molecules at room temperature
• Surface tension is the force that causes the surface of a liquid to contract
• Greater intermolecular force of attraction in a liquid results in higher surface tension
• Viscosity is a liquid's resistance to flow between molecules when they move past each other
• Greater resistance in flowing results in higher viscosity of the liquid
• Vaporization is a change of state from liquid to gas, including evaporation and boiling
• Volatile liquids evaporate readily due to weak intermolecular forces of attraction
• Boiling point is the temperature when the vapor pressure of a liquid equals the atmospheric pressure
• Heat of vaporization is the amount of heat needed to vaporize a given amount of liquid at its boiling point
• Amorphous solids have fixed shape and volume but their particles are not arranged in regular geometric patterns
• Crystalline solids have distinctive internal structures with distinct surfaces and intersecting faces at characteristic angles
• Amorphous solids have particles trapped in a disarranged characteristic manner of liquids
• Examples of amorphous solids are glass, rubber, gels, some plastics, and nanostructured materials
• Crystalline solids have a unit cell structure that can be simple or closed-packed
• There are four types of crystalline solids: Ionic Solids, Covalent Solids, Molecular Solids, and Metallic Solids
• Ionic solids have positive and negative ions held together by electrostatic attractions, resulting in high melting points
• Covalent solids contain a three-dimensional network of covalently bonded atoms
• Covalent solids are very hard, have high melting points, and low thermal conductivity
• Graphite is an exceptional covalent solid, composed of planar sheets of covalent crystals held together by noncovalent forces
• Molecular solids are soft, have low to moderately high melting points, and poor thermal and electrical conductivity
• Metallic crystals have a uniform distribution of atomic nuclei within a "sea" of delocalized electrons
• Metallic solids have high thermal and electrical conductivity, metallic luster, and malleability
• Phase changes involve absorption or release of heat
• Evaporation and melting processes absorb heat, while condensation and freezing release heat
• Sublimation is changing the phase of a substance from solid to gas without passing the liquid phase, involving the absorption of heat
• Deposition is changing the phase of a substance from gas to solid, involving the release of heat
• Phase changes are shown in diagrams that illustrate the effects of pressure and temperature on matter
• The triple point is where all three distinct phases of matter coexist, while the critical point is where liquid and gaseous phases merge into a single phase
• The stability of phases depends on pressure and temperature, with the gas phase being most stable at low pressure and temperature
• Heating and cooling curves show changes in temperature as substances undergo phase transitions
• Heating curves show the absorption of heat during melting and evaporation, while cooling curves show the release of heat during condensation and freezing
• Continued heating after complete melting increases the kinetic energy of liquid molecules, leading to a rise in temperature
• Ionic bond - formed when there is a transfer of electrons from a metal to a nonmetal. At room temperature, all ionic compounds are solids.
• Covalent bonds form between two atoms sharing one or more pairs of electrons.