6/23/2015  2 Handouts States of Matter Lecture Notes Intermolecular Forces Problem Set  Please bring your Chemistry I/II lab manual to chemistry topic lectures for this week and next week.

States of Matter Edward A. Mottel Department of Chemistry Rose-Hulman Institute of Technology

6/23/2015 States of Matter  Reading assignment: Fine, Beall & Stuehr, Chapter , 16.6, 17.2, ,  Phases of matter  Molecular interactions  Atomic measurements

6/23/2015 Phases of Matter PhaseCharacteristicsStructure Examples Gas fills any volumeminimal orderHe, O 3, UF 6 Liquid fills a specific volume short range ordering Br 2, H 2 O N 2 ( l ), glass Solid atoms & molecules in fixed positions crystalline short & long range ordering amorphous short range ordering NaCl, sucrose polyethylene clear polypropylene Plasma atomic particles no ordering nuceli & electrons What types of materials can you see through clearly?

6/23/2015 Phase Diagram  Indicates the stable phases of a compound as a function of temperature pressure  Points on the line indicate an equilibrium condition involving two or more phases.

6/23/2015 Phase Diagram  Normal melting point  Normal boiling point  Relative density of solid and liquid phases  Triple point  Critical point  Applications

6/23/2015 Phase Diagram Water Temperature Pressure gas liquid vapor pressure line solid liquid solid gas normal boiling point 1 normal melting point triple point (+0.01 °C, atm) critical point (374 °C, atm)

6/23/2015 Phase Diagram Water Temperature Pressure gas liquid solid normal boiling point 1 normal melting point triple point (+0.01 °C, atm) critical point (374 °C, atm) Identify the process of boiling. Identify the process of sublimation. How are the densities of water and ice related? What occurs beyond the critical point?

6/23/2015 Carbon Dioxide  Carbon dioxide facts Triple point: -57 °C, 5.2 atm Critical point: 31 °C, 72.9 atm Solid CO 2 sinks in liquid CO 2 Draw a phase diagram of carbon dioxide.

6/23/2015 Phase Diagram Carbon Dioxide Pressure Temperature 1

6/23/2015 Phase Diagram Carbon Dioxide Pressure Temperature gas liquid 1 solid Why is solid carbon dioxide called “dry ice”? Application: supercritical fluid

6/23/2015 Atomic and Molecular Interactions Species Type of InteractionMethod of Interaction Strength of Interaction (kJ mol -1 ) atoms / ions covalent bonds sharing of electrons between atoms single, double, triple bonds Single: Double: Triple: ionic bonds electrostatic attraction non-directional bonding E = k (q + q - ) / d dipole-dipole H-bond:5-50 others weaker atoms / ions / molecules van der Waal forces dipole-induced dipole weak dispersion forces very weak

6/23/2015 Covalent Bonds Electrons are Shared O H H O H H O O O O Double bonds are stronger than single bonds. Is intramolecular bonding stronger in water or dioxygen?

6/23/2015 Ionic Bonds Electrostatic Attraction Ca 2+ H+H+ Cl – E = k · q 1 · q 2 d Compounds with ionic bonds generally have high melting points.

6/23/2015 van der Waal Forces Dipole-Dipole: Hydrogen Bonding H H O H H O

6/23/2015 van der Waal Forces Dipole-Induced Dipole H H O O O

6/23/2015 van der Waal Forces Dispersion Forces O O O O Molecular compounds generally have low melting points. Is intermolecular bonding in liquid oxygen strong or weak? Which bond breaks when liquid oxygen boils?

Intermolecular and Intramolecular Forces What molecular interactions could occur and which are the strongest? Mercury doesn’t “wet” the surface of glass (silicon dioxide). Does water “bead up” on a clean or a dirty windshield? Why?

6/23/2015 The Chemical "Bond"  Electronegativity differences  Various strength of bonds covalent bonds ionic bonds polar covalent bond

6/23/2015 The Chemical "Bond"  Physical properties associated with phase & structure Surface tension, viscosity, mp, bp, vapor pressure The special role of hydrogen bonds

6/23/2015 Predict the Boiling Point Series 1Series 2 MWBPMWBP SiH 4 GeH 4 SnH 4 CH H2SH2S H 2 Se H 2 Te H2OH2O+100

6/23/2015 Electronegative Elements Nitrogen, Oxygen, Fluorine, (Sulfur, Chlorine) Hydrogen bonds form between molecules or ions containing very electronegative elements, and hydrogen bound to one of these electronegative elements H H O H H O

6/23/2015 The Effects of Hydrogen Bonding  Melting and boiling points Liquid water at room temperature  Solubility ammonia in water  Structure Ice is less dense than liquid water Helical structure of DNA

6/23/2015 Measurements  How are things measured? Distances between cities Dimensions of a football field The size of a coin The distance between atoms

6/23/2015 X-ray Diffraction  X-ray wavelength 10 – –11 meters nanometer (10 –9 m), nm Angstrom (10 –10 m), Å  The distance between atoms is in the same range.

6/23/2015 X-ray Diffraction

6/23/2015 X-ray Diffraction

6/23/2015 X-ray Diffraction

6/23/2015 X-ray Diffraction

6/23/2015 X-ray Diffraction incident wave  reflected wave   d n = 2d sin 

6/23/2015