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Forces of Attraction, Liquids, Solids, & Phase Diagrams. Forces of Attraction(13-2). In tra molecular forces – within molecules In ter molecular Forces– attractions between particles (three types) Dispersion Forces – found in all particles/more in larger particles - PowerPoint PPT Presentation
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Forces of Attraction, Liquids, Solids, & Phase Diagrams
Forces of Attraction(13-2)A. Intramolecular forces – within molecules
B. Intermolecular Forces– attractions between particles(three types) 1. Dispersion Forces – found in all particles/more in larger
particles2. Dipole – found in polar particles3. Hydrogen Bonds – found in polar particles with H bonded
to a “FON” element
C. Greater attractive forces between their particles give substances higher melting/boiling points (i.e. why F2 and Cl2 are gases, Br2 is a liquid and I2 is a solid)
Liquids (13-3)A. Surface tension – tendency of a liquid to “hold itself
together” (minimize surface area) — this is due to IM forces (COHESION)
B. Capillary action – movement of liquids up small diameter tubes• cohesive forces – IM forces• adhesive forces – attractive forces between the molecules
and a surface or containerC. Viscosity • measure of a liquids resistance to flow (syrup has a
higher viscosity than water) • substances with large IM forces tend to be highly viscous
Figure 4: It is possible to see that in water, the strength of the cohesion forces are larger than the strength of the adhesion forces. This results in the concave formation of water in the capillary tube. This is known as capillary attraction. Alternatively, the adhesion forces are evidently stronger than the cohesion forces which allows the mercury to bend in a convex formation away from the walls of the capillary tube. This is known as capillary repulsion.
Capillary Action
Viscosity
Solids (13-3)A. Density of solids –depends on the substanceB. Types of solids
1. Crystalline– They have a regular structure, in which the particles pack in a repeating pattern from one edge of
the solid to the other.
a. Ionic (ex: ??)b. Molecular (ex: ??) c. Atomic
–Covalent network (ex: ??)–Metallic (ex: ??)–Noble gases (ex: ??)
2. Amorphous (ex: ??) – literally, "solids without form") have a random structure, with little if any long-range order.
Diamond
Salt
sugar (C12H22O11)
Copper
Wax
(Ne, Ar, Kr, and Xe) at negative pressure and temperatures below the triple-point temperature
Phase Diagrams (13-4)A. Water’s versus carbon dioxide’s B. Shows three phases as they exist at
different pressure and temperature values (y and x axes)
C. Lines represent equilibrium between phases (or phase changes) Which are endothermic / exothermic?
D. Triple point – equilibrium between all three phases (“boiling ice water”)
Vapor Pressure (13-4)A. the tendency of particles in the liquid phase
to enter the gas phase at that temperatureB. open system–continuous evaporation/closed
system–equilibriumC. VP increases with increasing temp.D. a liquid boils when VP = atmos. press