CONDENSED STATES OF MATTER

Chapter 13

States of Matter:

______ - composed of particles packed closely together with little space between them. Solids maintain a _______ ____.

______ - any substance that flows. (A fluid) - particles are free to slide past one another and continual change their positions. Particles are in ______ ______ ______ .

______ - are fluids composed of particles in ______ ______ ______ . Gases are not touching most of the time.

Kinetic-Molecular Description of Liquids & Solids

Solids & liquids are ______ ______ atoms, ions, molecules are close to one another highly incompressible

Liquids & gases are ______ easily flow

______ ______ ______ in liquids & solids are strong

______ liquids diffuse into one another they are ______ in each other for example: water/alcohol gasoline/motor oil

______ liquids do not diffuse into each other they are ______ in each other for example: water/oil water/cyclohexane

Periodic Table Reminders

______ ______ - called groups or families. Elements in a group have similar chemical and physical properties

______ ______ - called periods, elements within a period have properties that change progressively across the table

Intermolecular forces, I.F.

depend on the shape of the molecules and polarity (dipole moments), Lewis structures and electronegativity

Table 13-1 Characteristics of solids, liquids, and gases

Ex. Sulfur hexafluoride

Ex. water

______ ______ __

______ attractions are the strongest.makes up ionic bondingtend to be crystalline solids (hard, but brittle)very high melting points

Na+Cl-Na+Cl-Na+Cl-Na+Cl-Na+Cl-Na+Cl-

Cl-Na+Cl-Na+Cl-Na+Cl-Na+Cl-Na+Cl-Na+ Na+Cl-Na+Cl-Na+Cl-Na+Cl-Na+Cl-Na+Cl-

ion-ion attractions

______ ______ ______

______ ______ attractions (fairly strong)happens with polar molecules b/c they have

permanent dipole moments H—Cl H—Cl δ+ δ- δ+ δ-

______ ______ ______ _

______ ______ – a special dipole attraction, stronger than normal dipole-dipole attractions - very strong attraction

~ 2 conditions: must have a ______ bonded to a H and at least one lone pair of electrons on N, O, F

δ+

δ- H . . l

H—N—H δ- :N –H δ+

δ+ l δ+ l H H δ+ δ+

______ ______ ______

London dispersion forces (the weakest), also called van der Waals attractions

______ ______ occurs in nonpolar molecules temporary dipole caused by interaction with

another moleculeboil and melt very easilyδ+ δ-

F—F F—F δ- δ+

Properties of liquids

Properties of liquids at constant temperature~ no definite ______ ~ definite ______

~ have surface tension, diffuse, medium density, viscosity, evaporation, capillary action, and vapor pressure. ______ of each depends on I.F.

1. ______ ______

Surface Tension - measure of the ______ ______ that occur at the surface of a liquid

molecules at surface of a liquid are only attracted in a down direction. Denser on top At surface, molecules are attracted downward, thus

liquid is denser on top water bugs

2. Viscosity

– ______ – how easily it flows~ stronger I.F. ______ ______ the liquid is~ geometry of molecule affects viscosity

(more complex shapes = more viscous) ~ very long chains – more viscous b/c longer

chains get tangled C—C—C—C—C—C—C—C —C—C—C—C

more viscous less viscous

3. ______ ______

– tendency of a liquid to be ______ or ______ by a very narrow tube - Stronger I.F. more cohesion

~ when a molecule has attraction for itself, it’s called ______

~ when a molecule has attraction for other molecules, it is ______

capillary rise implies adhesive > cohesive (water) capillary fall implies cohesive > adhesive (mercury)

4. _____ _

– when a liquid changes to the vapor phase at a temp. that is less than it’s boiling point.

Why? If the molecule can gain enough speed, they break through the liquid and go into the atmosphere

5. ______ ___

– the pressure of a gas that exists over its solid or liquid state. High I.F. = low Pvap

Does not depend on how much liquid/solid you have.

Pvap depends on the temp. and type of substance.

You have vapor pressure as long as there is evaporation of a liquid.

Higher Temperature = Higher vapor pressureBoiling occurs when the Pvap of liquid = Patm

The Liquid State

Vapor Pressure (High I.F. = low Pvapor )

______ ______ ______

~ All liquids have different boiling points: based on I.F. Higher I.F., higher the normal boiling point.

~ can separate liquids on the basis of their b.p. (distillation)

CH3OH has a lower boiling point than C2H5OH, so it changes to a gas first.

______ ______

– show the phase of matter at a variety of P and T. (pg 507)

~ Substances can be almost any phase, given the right P and T.

H2o is less dense in solid state (ice has lots of space in it), water has a negative slope between the solid & liquid on the phase diagram. Water is densest at 4oC.

______ ______ ______ _____

q = mcΔT q = heat m = mass c = specific heat ΔT = change in temp.

specific heat is the amount of energy needed to raise 1 g of a substance 1oC

If c is big, it’s hard to heat up or cool down. If less than one, easy to heat up or cool down.

During a phase change, the temp. stays the same. Still heating/cooling, but no temp. change due to the breaking down or forming of I.F.

______ ______

s melting (or fusion)ℓ ℓ s freezing ℓ g boiling

g condensation (liquefaction if forced to ℓoccur by pressure)

s g sublimationg s deposition

melt or evaporating (boiling) + qfreeze or condensing -q

q = mHf enthalpy of fusion

q = mHv enthalpy of vaporization

q = mHs enthalpy of sublimation (A-12)

 q is + if substance is melting or evaporating q is – if substance is freezing or condensing Ex. How much heat is required to raise the temp.

of 50.0 g of ice at –12.0oC to 120.0oC  

Trends in boiling points of Liquids

Gas MW BP(oC)

He 4 -269

Ne 20 -246

Ar 40 -186

Kr 84 -153

Xe 131 -107

Rn 222 -62

The boiling point increases in response to molecular size

The boiling point increases in response to molecular size

Compound MW(amu) B.P.(oC)

CH4 16 -161

C2H6 30 -88

C3H8 44 -42

n-C4H10 58 -0.6

n-C5H12 72 +36

In the Liquid State

Compound MW(amu) B.P.( C)

HF 20 19.5

HCl 37 - 85.0

HBr 81 - 67.0

HI 128 - 34.0

o

HF has the highest B.P. b/c of Hydrogen bonding. The rest increases in response to molecular size.

In the Liquid State

Compound MW(amu) B.P.( C)

H O 18 100

H S 34 - 61

H Se 81 - 42

H Te 130 - 2

o

2

2

2

2Water has the highest B.P. because of Hydrogen bonding. The rest increases b/c of increase in molecular size.

Various boiling points

Arrange the following substances in order of increasing boiling points.

C2H6, NH3, Ar, NaCl, AsH3

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Amorphous & Crystalline Solids

Amorphous solids ______ have a well ordered structure. Particles are irregularly arranged so IF vary in strength within a sampleEx.

Crystalline solids have well defined structures that consist of extended array of repeating units. Have defined IF.give X-ray difraction patterns ~ see Bragg equation in

bookEx.

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Structure of Crystals

unit cell - smallest repeating unit of a crystalEx. bricks are repeating units for buildings

7 basic crystal systems We do not need to learn these 7 now – just an FYI for

your future…

Types of Solids

4 Types of Solids: Ionic, Metallic, Molecular, Covalent

______ : positive and negative ions arranged in a specific structure. Electrostatic attractions are strong.

______ : metals where each valence electron is thought to belong to the entire structure. So metals are seen as a positive nuclei with a sea of electrons. The mobility of electrons helps explain the electrical conductivity of metals.

______ ______ : are solids made up of molecules that are next to each other in unit cells. The attractive forces between individual molecules are relatively weak. They are volatile and insulators. Simple covalent compounds usually form molecular solids

______ ______ : Network solids or giant molecules – individual atoms are covalently bonded to other atoms and those atoms are bonded to other atoms, etc. This makes covalent solids very hard with very high melting points. Most are nonconductors.

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Examples of Bonding in Solids

Ionic Solids ions occupy the unit cell Examples:

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Examples of Bonding in Solids

Metallic Solids positively charged nuclei surrounded by a sea of

electrons

positive ions occupy lattice positions

Examples:

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Examples of Bonding in Solids

Molecular Solids molecules occupy unit cells low melting points,volatile & insulators Examples:

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Examples of Bonding in Solids

Covalent Solids atoms that are covalently bonded to one another Examples:

Compound Melting Point (oC)LiF 842LiCl 614LiBr 547LiI 450CaF2 1360CaCl2 772CaBr2 730CaI2 740

Bonding in Solids - Variations in Melting PointsIonic Solids

Melt at fairly high temps b/c the attraction between ions are much stronger than in molecular solids but weaker than in covalent solids. Attractive forces increase as charges on ions increase & their radii decrease.

Melting points vary widely b/c there are large variations in the strengths of metallic bonding. Most metals have fairly high melting points but Mercury is a liquid at room temp.

Metal Melting Point (oC)

Na 98Pb 328Al 660Cu 1083Fe 1535W 3410

Bonding in Solids - Variations in Melting PointsMetallic Solids

Have low melting points (most < 300o C ) because the attractive forces between the molecules are rather weak.

Compound Melting Point (oC)

ice 0ammonia -77.7benzene, C6H6 5.5napthalene, C10H8 80.6benzoic acid, C6H5CO2H 122.4

Bonding in Solids - Variations in Melting Points Molecular Solids

Melt at high temps (most > 1500o C ) because the attractive forces between the individual particles are very strong.

Substance Melting Point (oC)

sand, SiO2 1713carborundum, SiC ~2700diamond >3550graphite 3652-3697

Bonding in Solids - Variations in Melting Points Covalent Solids

Brief summary

Intermolecular attractions from strongest to weakest Ion-Ion: ionic compounds (metal/nonmetal)

Hydrogen bonding: H attached to a N, O, or F and lone pair of e- on the central atom

Dipole – Dipole: polar compounds

London Dispersion Forces (induced dipole): all compounds exhibit this, but it is most important with non-polar compounds.

Effects of intermolecular attractions

The compound that has the highest boiling pt, melting pt, and heat of vaporization corresponds to the compound with the strongest I.F.

The highest vapor pressure corresponds to the lowest intermolecular attractions.

If two compounds are nonpolar, the one with the greatest molecular mass has the greater London Forces.

If two compounds are ionic, the one with the greatest charge ions has the greater I.F. If same charge, the smallest ions have the greatest I.F.

For many years, the world’s record for flying gliders was 60,000 ft. It was set by a Texan who flew into an updraft in front of an approaching storm. The pilot had to fly out of the updraft and land, not because he was our of air (there was still plenty of air in his compressed air bottle) but because he was not wearing a pressurized suit. What would have happened to the pilot’s blood if he had continued to fly higher?