Download presentation
Presentation is loading. Please wait.
1
Liquids and Solids “CONDENSED STATES OF MATTER”
2
Intra- vs. Inter- intramolecular forces inside molecules
hold atoms together into molecule intermolecular forces between molecules get weaker as phase changes from S – L – G Generally, intermolecular forces are much weaker than intramolecular forces.
3
Orientation of Polar Molecules in a Solid
Dipole-Dipole Forces Attractive forces between polar molecules Orientation of Polar Molecules in a Solid
4
happens between H and N, O, or F
Hydrogen Bonding happens between H and N, O, or F very strong type of dipole-dipole attraction because bond is so polar because atoms are so small
5
Hydrogen Bonding Bonding between hydrogen and more electronegative neighboring atoms such as oxygen and nitrogen Hydrogen bonding between ammonia and water
6
London Dispersion Forces
The temporary separations of charge that lead to the London force attractions are what attract one nonpolar molecule to its neighbors. increase with the size of the molecules. in every molecular compound only important for nonpolar molecules and noble gas atoms weak, short-lived caused by formation of temporary dipole moments Fritz London
7
London Dispersion Forces
8
Relative Magnitudes of Forces
The types of bonding forces vary in their strength as measured by average bond energy. Strongest Weakest Covalent bonds (400 kcal/mol) (intramolecular) Hydrogen bonding (12-16 kcal/mol ) (intermolecular) Dipole-dipole interactions (2-0.5 kcal/mol) (intermolecular) London forces (less than 1 kcal/mol) (intermolecular)
9
London Forces in Hydrocarbons
Dispersion forces usually increase with molar mass.
10
Boiling point as a measure of intermolecular attractive forces
11
Practice which has highest boiling pt?
HF, HCl, or HBr? Identify the most important intermolecular forces : BaSO4 H2S Xe C2H6 P4 H2O CsI HF ionic dipole-dipole London Dispersion London Dispersion London Dispersion H-bonding ionic
12
Which has stronger IMF’s?
CO2 or OCS CO2: nonpolar so only LD OCS: polar so dipole-dipole PF3 or PF5 PF3: polar so dipole-dipole PF5: nonpolar so only LD SF2 or SF6 SF2: polar so dipole-dipole SF6: nonpolar so only LD SO3 or SO2 SO3: nonpolar so LD only SO2: polar so dipole-dipole ? ? ? ?
13
DO WE GET IT? To be collected!
Please begin the following problems. You may work cooperatively on this assignment. Problems: pg. 475 #12, 20, 30, 32, 34 and 36 (a,b and d only!) To be collected!
14
Some Properties of a Liquid
Surface Tension: The resistance to an increase in its surface area (polar molecules, liquid metals). Strong intermolecular forces High surface tension =
15
EMOO BUG Surface of water behaving like it had an “elastic skin”
16
attracted to each other
Capillary Action: Spontaneous rising of a liquid in a narrow tube. Cohesion is the intermolecular attraction between like molecules Adhesion Cohesion Adhesion is an attraction between unlike molecules attracted to glass attracted to each other
17
Properties of a Liquid Viscosity: Resistance to flow
High viscosity is an indication of strong intermolecular forces
18
Which of the following consistently have the highest melting points?
Metals Salts Molecular crystals Alkanes Hydrogen-bonded compounds. Answer: B
19
How sharp are you? Gases can be compressed more easily than liquids
because: Gas molecules are smaller than liquid molecules B. The kinetic energy of gas molecules is higher than that found in liquids The average intermolecular distances are greater in gases than those found in liquids. Intermolecular forces increase as gas moleculues are brought closer together. E. None of the above. Answer: C In a gas, the molecules are separated by a large distance and are able to be compressed by increasing the pressure. They move independently of one another because there is no appreciable intermolecular interactions among them.
20
In which of the following are the intermolecular
forces listed from the weakest to the strongest? Dipole-dipole>London>hydrogen bonds London<dipole-dipole<hydrogen bonds Hydrogen bonds<dipole-dipole<London London>hydrogen bonds>dipole-dipole London>Javier bonds>dipole-dipole>Ali forces Answer: B
21
Which of the following compounds will NOT hydrogen- bond>?
CF4 CH3OH H2NCH2CH2CH3 HOCH2CH2OH HClO Answer: A
22
Water has a higher capillary action than mercury due to:
Higher dipole-dipole forces between the water molecules Strong cohesive forces within water. Very significant induced intermolecular attractions. Weak adhesive forces in water Strong cohesive forces in water which work with strong adhesive forces. Answer: E. The strong adhesive forces leads to a creeping effect as water moves up the narrow tubing and the strong cohesive forces attempt to minimize the surface area.
23
Small drops of water tend to bead up because of:
High capillary action the shape of the meniscus The resistance to increased surface area. Low London dispersion forces Weak covalent bonds. Answer: C. This is a description of surface tension, which is a result of high dipole-dipole forces between water molecules. These intermolecular forces are also called…..hydrogen bonds!
24
Several liquids are compared by adding them to a series
of 50 mL graduated cylinders, then dropping a steel ball of uniform size and mass into each. The time required for the ball to reach the bottom of the cylinder is noted. This is a method used to compare the differences in a property of liquids known as: Surface tension Buoyancy Capillary action Viscosity Surface contraction Answer: D. The resistance to flow of any fluid is called viscosity. As You would predict, liquids with high viscosity (ex: maple syrup) have large intermolecular forces.
25
General Classification of Solids
Crystalline Solids: Well-ordered, definite arrangement of atoms. (Examples- metals, H2O, diamond) Amorphous: No pattern to the arrangement of particles. (Examples- glass, plastic, wax)
26
Representation of Components in a Crystalline Solid
Lattice: A 3-dimensional system of points designating the centers of components (atoms, ions, or molecules) that make up the substance.
27
Types of Crystalline Solids
There are four types of crystalline solid: - Molecular (formed from atoms or molecules) - usually soft with low melting points and poor conductivity. - Covalent network (formed from atoms) - very hard with very high melting points and poor conductivity. - Ionic (formed form ions) - hard, brittle, high melting points and poor conductivity. - Metallic (formed from metal atoms) - soft or hard, high melting points, good conductivity, malleable and ductile.
28
Bonding in Crystalline Solids
Know these!! Metallic bonds are formed from metal nuclei floating in a sea of electrons.
29
Crystalline Solids Molecular Covalent Network Ionic Metallic
30
Metal Alloys Substitutional Alloy: some metal atoms replaced by others of similar size. brass = Cu/Zn
31
Metal Alloys (continued)
Interstitial Alloy: Interstices (holes) in closest packed metal structure are occupied by small atoms. steel = iron + carbon
32
Phase Changes & Energy Endothermic: melting, evaporating/boiling & sublimation Exothermic: freezing, condensation, & deposition
33
Phase Changes & Energy heat of vaporization: the heat energy required to evaporate a given mass of liquid at a constant temperature heat of fusion: the heat energy required to melt a given mass of solid at a constant temperature The temperature, (average KE), during a phase change (such as boiling) does not change! Any heat added during boiling gives more molecules enough energy to escape the liquid. Heating Curve
34
Phase Changes & Energy Generally, it will take more heat to vaporize a liquid than to melt a solid… (∆H(vap) > ∆H(fusion) ) Why? Every intermolecular bond is broken when vaporizing, but only some of the intermolecular forces break when melting solids. ?
35
Practice Time: Please attempt the following problems
(at your workstations!): pg : 72, and 88.
36
Gases can be liquefied by: increasing pressure at some temperature.
Liquefying Gases Gases can be liquefied by: increasing pressure at some temperature. decreasing the temperature at some pressure. - Critical temperature: the highest temperature at which a substance can remain a liquid regardless of the pressure applied. - Critical pressure: the pressure needed at the critical temperature.
37
Phase Diagrams Shows the relationship between the 3 phases of matter at various temperatures and pressures. Triple Point: All 3 phases of matter at equilibrium. Critical Point: The highest temperature at which the liquid phase can exist.
38
Phase Diagrams of H2O and CO2
Notice the slope of the solid–liquid equilibrium line.
39
Practice Time: Please attempt the following problems. You may scatter and work with anyone you please. pg. 480: #91.
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.