| Question | Answer |
| Solids | 1. Covalent Network
2. Ionic
3. Metallic
4. Molecular Covalent (3 types of IMFs) |
| covalent network | -the simultaneous attraction by covalent bonds of an atom by adjacent atoms within a 3-D lattice of atoms
-very hard, very high melting point, insoluble in most ordianry solvents, nonconductors of electricity (b/c few open electrons) |
| ionic | -simultaneous attraction of ion by surrounding ions of opposite charge within an ionic crystal lattice
-crystalline solids, high melting and boiling points, dissolve in polar liquids to form conducting solution, electrical conductors as liquid |
| metallic forces | -simultaneous attraction of free valence electrons by metallic cations
-lustrous, malleable, good electrical conductors, wide range of melting points
-electron sea models |
| electron sea model | positive cations surrounded by a "sea" of MOBILE electrons |
| molecular covalent | exists between nonmetals
-Hydrogen bonding
-Dipole-Dipole Forces
-London dispersion forces |
| Hydrogen bonding | -simultaneous attraction of a hydrogen ion (proton) by the electron pairs of adjacent N, O, F atoms
-high melting solids, gases or liquids because of relatively strong intermolecular attraction |
| Dipole-Dipole Forces | -the simultaneous attraction of a molecular dipole by the surrounding molecular dipoles.
-a weak intermolecular force which exists in addition to the stronger dispersion forces, low melting solids, liquids,and gases |
| intermolecular forces | weak interactions that occur between molecules |
| surface tension | resistance of a liquid to an increase in its surface area |
| capillary action | the spontaneous rising of a liquid in a narrow tube [cohesive / adhesive] |
| cohesive forces | the intermolecular forces among the molecules of the liquid |
| adhesive forces | the forces between the liquid molecular and their container |
| viscosity | a measure of a liquid's resistance to flow
-favor liquids with high IMF |
| crystalline solids | highly regular arrangement of of their components |
| amorphous solids | considerable disorder in their structures |
| lattice | a 3D system of points designating the positions of the componenets (atoms, ions, or molecules) that make up the substance |
| unit cell | the smallest repeating unit of the lattice |
| X-RAY diffraction | occurs when beams of light are scattered from a regular array of points in which spacing between the components are comparable with the wavelength of the light
-used to determine the structures of crystalline solids |
| ionic solids | ions at the points of the lattice that describes the structure of the solid (NaCl) |
| molecular solids | has discrete covalently bonded molecules at each of its lattice points (sucrose, ice) |
| atomic solids | has atoms at the lattice points that describe the structure of the solid |
| alloy | a substance that contains a mixture of elements and has metallic properties |
| substitutional alloy | some of the host metal atoms are replaced by other metal atoms of the same size (brass) |
| intersititial alloy | formed when some of the interstices (holes) in the closet packed metal structure are occupied by small atoms (steel) |
| silica | -fundamental silicon-oxygen compound
-SiO2 |
| silicates | -found in most rocks, soils, and clays
-interconnected SiO4 Tetrahedra
-contain silicon-oxygen anions
-salts containing metal cations and polyatomic silicon-oxygen anions |
| glass | -amorphous solid
-results when silica is heated above its melting point (about 1600'C) and cooled rapidly
-homogeneous noncrystalline "frozen solution" |
| ceramic | -typically made from clays (which contain silicates) and hardened by firing at high temperatures
-nonmetallic materials that are strong, brittle, and resistant to heat and attack by chemicals
-heterogeneous noncrystalline "frozen solution" |
| semiconductor | -a material which has electrical conductivity between that of a conductor such as copper and an insulator such as glass.
-the conductivity increases with increasing temperature, behaviour opposite to that of a metal |
| n-type semiconductor | substance whose conductivity is increased by doping it with atoms having more valence e- than the atoms in the host crystal
-extra e- close in energy to conduction bands and are easily excited into these levels where they can conduct an electrical curren |
| p-type semiconductor | -semiconductor doped with atoms having fewer valence e- than the atoms of the host crystal
-so named because the positive holes can be viewed as the charge carriers |
| p-n junction | a small # of e- migrate from the n region into the p region, where there are vacancies in the low-energy molecular orbitals
-effect is to place - on the p region (since it now has surplus e-) and + on the n region (since it has lost e-s, leaving holes) |
| evaporation or vaporization | molecules of a liquid can escape the liquids surface and form a gas
endothermic because energy is required to overcome the relatively strong IMF in the liquid |
| heat of vaporization | the energy required to vaporize 1 mole of a liquid at a pressure of 1 atm |
| vapor | substance that is liquid at room temperature (25'C and 1 atm) but evaporated |
| condensation | the process by which vapor molecules re-form a liquid |
| equilibrium | at this point no further net change occurs in the amount of liquid or vapor because the two opposite forces exactly balance each other |
| vapor pressure | the pressure of the vapor present at equilibrium
-increases significantly with temperature
-favors weak IMF |
| volatile | -liquids with high vapor pressures
-they evaporate rapidly from an open dish
-favor weak IMF (bigger drop - particles able to escape at room temp) |
| sublimation | the process by which a solid goes directly to the gaseous state without passing through the liquid state
-dry ice (solid carbon dioxide) |
| heating curve | a plot of temperature versus time for a process where energy is added at a constant rate |
| heat of fusion | the enthalpy change that occurs at the melting point when a solid melts |
| normal melting point | the temperature at which the solid and liquid states have the same vapor pressure under conditions where the total pressure is 1 atm |
| normal boiling point | the temperature at which the vapor pressure of the liquid is exactly 1 atm
-favors larges e- cloud -> strongest LDF |
| supercooled | -water cooled below 0'C at 1 atm & remain liquid
- as it is cooled the water may not achieve the degree of organization necessary to form ice at 0'C
-At some point correct ordering occurs & ice forms, release energy - bring temp to mp |
| superheated | -raised to temperatures above its boiling point
-occur because bubble formation in the interior of the liquid requires that many high-energy
-vapor pressure is greater than the atm |
| bumping | superheated liquid
-once a bubble does form, since its internal pressure is greater than that of the atm, it can burst before rising to the surface, blowing the surrounding liquid out of the container |
| phase diagram | way of representing the phases of a substance as a function of temperature and pressure
-describes conditions and events in a closed system
-Water - negative slope (liquid more compact than solid) |
| closed system | no material can escape into the surroundings and no air is present |
| triple point | solid, liquid water have identical vapor pressures |
| critical temperature | the temp above which the vapor cannot be liquefied no matter what pressure is applied |
| critical pressure | the pressure required to produce liquefication at the critical temperature |
| critical point | critical temp and critical point |
| increase rate of evaporation | 1. increase surface area
2. increase temperature
3. increase wind currents
4. lower pressure
-a greater fraction of molecules can escape - Maxwell-Boltzmann Distribution |
| dynamic equilibrium | rates of opposing reactions are equal (evaporation & condensation) |
| evaporation v boiling | -phases changes (l -> g)
-endothermic (absorb heat to break IMF)
-boiling has bubbles
-evaporation occurs @ the surface/boiling occurs throughout
-evaporation, only a few particles have sufficient KE to vaporize; whereas with boiling most of the parti |
| to boil | reduce pressure in surrounding
heat it |
| gas | if something is gas at room temp |
| corner atom | shared 8 ways |
| center of face | shared 2 ways |
| center of edge | shared 4 ways |
| interior of atom | shared 1 way |
| freezing point depression | addition of non-volatile solute LOWERS the freezing point of the solvent (harder)
-small ponds freeze easier than oceans // dissolved ions have lower freezing point |
