IMF’s, Solids, and LiquidsIMF’s, Solids, and Liquids

Ch. 11 in TextbookCh. 11 in Textbook

msconti.blogspot.com

I. Intermolecular Forces (IMF’s)I. Intermolecular Forces (IMF’s)

attractions between attractions between separateseparate molecules, not bondsmolecules, not bonds

relatively weakrelatively weak occur based on molecular occur based on molecular

polarity and/or chargepolarity and/or charge the strength determines the strength determines

substance’s phase, b.p., m.p., substance’s phase, b.p., m.p., vapor pressure, etc.vapor pressure, etc. itl.chem.ufl.edu

HW: 11.4, 11.6

science.uwaterloo.ca

1. Ion-Dipole Forces (AKA 1. Ion-Dipole Forces (AKA Molecule-Ion Attractions)Molecule-Ion Attractions)

between an ion (full between an ion (full charge) and the charge) and the δδ+ or + or δδ- - of a polar moleculeof a polar molecule

usually the polar usually the polar molecule is water acting molecule is water acting as a solventas a solvent

the greater the the greater the magnitude of the ionic magnitude of the ionic charge and/or the partial charge and/or the partial charges, the stronger the charges, the stronger the IMF’sIMF’s chem.purdue.edu

chemprofessor.com

2.2. van der Waals Forcesvan der Waals ForcesA) Dipole-Dipole ForcesA) Dipole-Dipole Forces

a dipole (2 poles) is a polar a dipole (2 poles) is a polar moleculemolecule

attractions between polar attractions between polar moleculesmolecules

relatively strong, but relatively strong, but technically weaker than ion-technically weaker than ion-dipole forcesdipole forces

the higher the value of the higher the value of μμ (dipole moment), the higher the (dipole moment), the higher the IMF’s (for similar mass/size IMF’s (for similar mass/size molecules)molecules) chemtext.blogspot.com

chem.unsw.edu.au

B) Hydrogen BondingB) Hydrogen Bonding NOT a bondNOT a bond when H is bonded to very EN when H is bonded to very EN

elements (N,O,F, ONLY) a elements (N,O,F, ONLY) a “super dipole” is formed“super dipole” is formed

usually NHusually NH33, H, H22O, and HFO, and HF this leads to unusually high this leads to unusually high

dipole-dipole attractions and dipole-dipole attractions and thus, unusually high b.p.’sthus, unusually high b.p.’s

also results in ice being less also results in ice being less dense than waterdense than water

weren’t you listening, I said it’s weren’t you listening, I said it’s “NOT a bond!”“NOT a bond!”

chemed.chem.wisc.edu

yellowtang.org

C) London Dispersion Forces (AKA C) London Dispersion Forces (AKA Weak Forces)Weak Forces)

occurs between occurs between nonpolarnonpolar molecules molecules

helps when molecules helps when molecules are close to one anotherare close to one another

results from results from momentary/temporary/ momentary/temporary/ induced dipolesinduced dipoles

itl.chem.ufl.edu

the more you can distort an the more you can distort an atom or molecule’s atom or molecule’s electron cloud distribution, electron cloud distribution, the more the more polarizablepolarizable it is it is

larger/massive larger/massive atoms/molecules are more atoms/molecules are more polarizablepolarizable

thus, larger thus, larger atoms/molecules have atoms/molecules have stronger IMF’sstronger IMF’s

ex) halogensex) halogens elmhurst.edu

cactus.dixie.edu

C

NOTE: all molecules have NOTE: all molecules have London dispersion forces!London dispersion forces!

when molecules are of when molecules are of similar size, polarity similar size, polarity determines the strength of determines the strength of IMF’sIMF’s

when molecules differ greatly when molecules differ greatly in size, then polarizability in size, then polarizability determines the strength of determines the strength of IMF’sIMF’s

phys.bspu.unibel.by

HW: 11.8, 11.10, 11.12 (a)-(c), 11.18, 11.22

IMF flow chartIMF flow chart

do activity in lab area do activity in lab area as a group of 4as a group of 4

have chart “Schu have chart “Schu approved”approved”

copy as notescopy as notes

adroll.com

II.II. Properties of LiquidsProperties of Liquids1. Viscosity1. Viscosity

resistance to flowresistance to flow high viscosity- molasses, syruphigh viscosity- molasses, syrup low viscosity- ethanol, waterlow viscosity- ethanol, water based not only on the strength based not only on the strength

of the IMF’s, but also structural of the IMF’s, but also structural features that may cause features that may cause entanglement of moleculesentanglement of molecules

as temp. inc., viscosity dec. due as temp. inc., viscosity dec. due to the breaking of IMF’sto the breaking of IMF’s

syntheticperformanceoil.com

2. Surface Tension2. Surface Tension

due to the imbalance of due to the imbalance of IMF’s within a liquidIMF’s within a liquid

there is a net there is a net downwarddownward pull of surface pull of surface moleculesmolecules

results in results in close packingclose packing of molecules at the of molecules at the surface, forming a surface, forming a “skin”“skin”

fizyka.phys.put.poznan.pl

technically, surface technically, surface tension is defined as the tension is defined as the energy required to energy required to increase the surface area increase the surface area of a liquid by a unit of a liquid by a unit amountamount

units: J/munits: J/m22

quest.nasa.gov

water has a high surface water has a high surface tension due to high tension due to high IMF’sIMF’s

mercury has an even mercury has an even higher surface tension higher surface tension due to metallic bondingdue to metallic bonding

ramehart.com

HW: 11.23

3. Cohesion and Adhesion3. Cohesion and Adhesion

cohesioncohesion = IMF’s between = IMF’s between molecules of the same molecules of the same substancesubstance

adhesionadhesion = IMF’s between = IMF’s between molecules and other molecules and other surfacesurface

although both types of although both types of forces are present, mercury forces are present, mercury has greater cohesive forces has greater cohesive forces than water whereas water than water whereas water has greater adhesive forces has greater adhesive forces than mercurythan mercury

cr4.globalspec.com

4. Capillary Action4. Capillary Action

molecules of liquid rising up molecules of liquid rising up a narrow tubea narrow tube

mechanism = adhesion mechanism = adhesion causes water to stick to tube causes water to stick to tube which increases the surface which increases the surface area; in order to reduce area; in order to reduce surface area, surface tension surface area, surface tension pushes water up tube against pushes water up tube against gravitygravity

ex) chromatography; water ex) chromatography; water in plant rootsin plant roots

cc.gatech.edu

HW: 11.24

III. Phase ChangesIII. Phase Changes

chemistry.wustl.edu

HW: 11.28

1. Heating/Cooling Curves1. Heating/Cooling Curves

physicalweeding.com

heat is ALWAYS being added!heat is ALWAYS being added! when temperature increases, the when temperature increases, the

KE (energy of motion) of the KE (energy of motion) of the particles must be increasing (PE particles must be increasing (PE remains the same)remains the same)

when temperature remains the when temperature remains the same, the KE of the particles same, the KE of the particles must remain the same; thus, PE must remain the same; thus, PE (energy of position) increases as (energy of position) increases as the phase change occursthe phase change occurs

funsci.com

ΔHΔHvapvap > ΔH > ΔHfusfus q = mCΔT used for q = mCΔT used for

calculating heat during calculating heat during temp. changestemp. changes

where where q = heat change in Jq = heat change in Jm = mass in gm = mass in gC = specific heat in C = specific heat in

J/g·K or J/g·ºC J/g·K or J/g·ºC ΔT = temp change ΔT = temp change (T(Tff – – TTii) in K or ºC ) in K or ºC

mrbigler.com

HW: 11.34

2. Vapor and Vapor Pressure2. Vapor and Vapor Pressure vaporvapor = gaseous form of a = gaseous form of a

substance normally found as substance normally found as a liquida liquid

vapor pressurevapor pressure = pressure due = pressure due to vaporto vapor

evaporationevaporation = vaporization of = vaporization of surface molecules of liquidsurface molecules of liquid

boilingboiling = vaporization = vaporization throughout liquid, occurs throughout liquid, occurs when the when the vapor pressure = vapor pressure = atmospheric pressureatmospheric pressure

kidsgeo.com

STORYTIME!STORYTIME!

cityoflawton.ok.us

#1 Water in a Beaker#1 Water in a Beaker

@ room temp and @ room temp and standard pressurestandard pressure

what happens to it?what happens to it?

goldcoast.qld.gov.au

#2 Stoppered Flask of Water#2 Stoppered Flask of Water

@ room temp and @ room temp and standard pressurestandard pressure

what happens to it?what happens to it?

daigger.com

#3 Ethanol Vs. Water#3 Ethanol Vs. Water

@ room temp and standard pressure@ room temp and standard pressure what happens?what happens? volatilityvolatility = the ability to evaporate easily = the ability to evaporate easily

outboardmotoroilblog.com images.veer.com

#4 Heated flask of Water#4 Heated flask of Water

constant heating @ constant heating @ standard pressurestandard pressure

what happens to it?what happens to it? normal boiling pointnormal boiling point = =

temperature at which temperature at which the v.p. of water equals the v.p. of water equals 1 atm (standard 1 atm (standard pressure)pressure)

demo.physics.uiuc.edu

HW: 11.39, 11.42

3. Vapor Pressure Curves3. Vapor Pressure Curves

kentchemistry.comHW: 11.43

4.4. Phase DiagramsPhase Diagrams

from textbook

triple pointtriple point = temp. and = temp. and pressure at which all 3 pressure at which all 3 phases exist in phases exist in equilibriumequilibrium

critical pointcritical point = the = the highest temp. and highest temp. and pressure at which a pressure at which a liquid can existliquid can exist

supercritical fluidsupercritical fluid = = liquid and gas phases liquid and gas phases are indistinguishableare indistinguishable definitiontees.com

HW: 11.36, 11.47, 11.48, 11.50, 11.52

IV.IV. Structures of SolidsStructures of Solids1. Crystalline vs. Amorphous1. Crystalline vs. Amorphous

crystallinecrystalline = well-defined = well-defined arrangement of atoms or arrangement of atoms or molecules (def. attractions = molecules (def. attractions = def. m.p.)def. m.p.)

ex) quartz, diamond, ionic ex) quartz, diamond, ionic solidssolids

amorphousamorphous = no well-defined = no well-defined arrangement of atoms or arrangement of atoms or molecules (indef. attractions = molecules (indef. attractions = softens over temp. range, no softens over temp. range, no distinct m.p.)distinct m.p.)

ex) glass, rubberex) glass, rubber

ndt-ed.org

HW: 11.53

2. Unit Cells2. Unit Cells

unit cellunit cell = the “bricks” = the “bricks” that make up a that make up a crystalline solid; the crystalline solid; the smallest repeating unit smallest repeating unit in a crystal latticein a crystal lattice

fkp.jku.at

A) Primitive CubicA) Primitive Cubic

the lattice points are at the lattice points are at the corners and are the corners and are actually shared by 8 actually shared by 8 atoms!atoms!

1/8 of an atom x 8 1/8 of an atom x 8 corners = 1 atomcorners = 1 atom

ece-www.colorado.edumrsec.wisc.edu

B) Body-Centered CubicB) Body-Centered Cubic

lattice points are at the lattice points are at the corners corners andand at the center at the center

1/8 of an atom x 8 1/8 of an atom x 8 corners + 1 atom = corners + 1 atom = 2 atoms2 atoms

ece-www.colorado.edu

mrsec.wisc.edu

C) Face-Centered CubicC) Face-Centered Cubic lattice points are at the lattice points are at the

corners and each corners and each face/sideface/side

½ of an atom x 6 sides + ½ of an atom x 6 sides + 1/8 atom x 8 corners = 1/8 atom x 8 corners =

4 atoms 4 atoms

ece-www.colorado.edu

mrsec.wisc.edu HW: 11.56, 11.58

3. Bonding in Solids3. Bonding in Solids molecular solidsmolecular solids ionic solidsionic solids metallic solidsmetallic solids covalent-network solids = covalent-network solids =

continuous lattice continuous lattice structure of covalent structure of covalent bonds (no molecules); bonds (no molecules); rigid and dense with high rigid and dense with high m.p.’s (FYI, must break m.p.’s (FYI, must break bonds to melt!)bonds to melt!)

ex) SiOex) SiO22, C (diamond), C , C (diamond), C (graphite), C (buckyballs)(graphite), C (buckyballs)

chem.ufl.edu

HW: 11.69, 11.70

legacy.co.mohave.az.us