Solids

Molecular Solids Covalently bound molecules held together by intermolecular forces

Molecular Solids Non-conductors Insoluble in water mostly Low MP & BP Held by intermolecular F

Intermolecular Forces Instantaneous weak forces that hold one molecule to another or to another part of itself

Intermolecular Forces H-bond Dipole-dipole Dipole-induced dipole London dispersion

Network Molecular Solids Bound by a continuous network of covalent bonds High MP, insoluble, non- conductor

Ionic Solids Ions or ionic compounds held together by electrostatic charge F attraction = Kq 1 q 2 /d 2

Ionic Solids Non-conductors as solids Conductors in solution Soluble in water mostly Very high MP & BP Brittle

Metallic Solids Conductors, insoluble in water mostly, high MP & BP, held by gravitational type force F attraction = Gm 1 m 2 /d 2

Crystal Solid Any substance that has a well defined crystal structure

Crystal Lattice The three dimensional arrangement of unit cells in a crystal structure

Unit Cell The smallest repeating unit that a crystal structure can be divided into

Crystal Structures CubicMonoclinic TetragonalTriclinic Orthorhombic Hexagonal Rhombohedral

Cubic All angles = 90 o All sides are = All faces are squares

Tetragonal All angles = 90 o 2 side sets are =, third  1 set of opposing squares 2 sets opposing rectangles

Orthorhombic All angles = 90 o all 3 side sets are  3 unequal sets opposing rectangles

Hexagonal All angles = 90 o or 120 o 1 set of opposing hexagons 3 sets opposing rectangles

Monoclinic 2 sets of angles = 90 o third set  90 o 1 set of opposing parallel 2 sets opposing rectangles

Triclinic No angles = 90 o 3 unequal sets of opposing parallelograms

Rhombohedral No angles = 90 o All sides = 3 sets of opposing congruent rhombuses

Simple Cube Unit cell with one atom at each vertex 1 atom/cell

Body Centered Cube BCC Unit cell with one atom at each vertex & one atom in the center of the cube 2 atoms/cell

Face Centered Cube FCC or CCP Unit cell with one atom at each vertex & one atom on each face of the cube 4 atoms/cell

The density of iron in its normal state of BCC is 7.86 g/mL. Calculate its density in the FCC state

Drill: List & describe the 7 crystal structures

Hydrated Crystal A solid with water in the crystal CuSO 4 *5H 2 O

Anhydrous Solid A crystal without water

Hygroscopic Crystals that absorb moisture from the air

Deliquescent Crystals that absorb enough moisture from the air to liquify

Efflorescent Crystals that give up water to the surroundings

Polymorphous When a single substance can have multiple crystal structures

Isomorphous When different substances have the same crystal structure

Amorphous Solid A solid w/o a well defined crystal structure Super-cooled liquid

Liquid Crystals Part solid & part liquid Has a well defined crystal structure in 1 or 2 but not all 3 dimensions

Smectic Liquid crystal that have a well defined crystal structure in 2 dimensions

Nematic Liquid crystals that have a well defined crystal structure in only 1 dimension

Liquid A substance that holds together loosely, but has no structure in any dimension

Solid Definite size & shape Particles vibrate about fixed points

Liquid Definite size but no shape Particles vibrate about moving points

Gas No definite size or shape Particles move at random

Melting Point Temperature at which the solid phase & liquid phase are at equilibrium MP & FP are equal

Melting Point Temperature at which the vapor pressure of a solid = the vapor pressure of its liquid phase

Boiling Point Temperature at which the liquid phase & gaseous phase are at equilibrium

Boiling Point Temperature at which the vapor pressure of a liquid = the vapor pressure of its gaseous phase or atmospheric P

Adhesion The attraction of particles from different substances to each other

Cohesion The attraction of particles of the same substance towards each other

Capillarity The movement of a liquid up a thin tube due to adhesion & cohesion

Surface Tension Pressure on the surface of a liquid caused by the uneven forces acting on the surface molecules

Vapor Pressure The pressure caused by the evaporated particles in the vapor above a liquid

Intermolecular Forces Weak temporary attractions between atoms from one molecule to another or another part of a larger molecule

Intermolecular Forces Hydrogen-bond Dipole-dipole Dipole-induced dipole London dispersion forces

Hydrogen Bond Strongest of the intermolecular forces Occurs when H is bound to one highly EN element & connects to another

Dipole-Dipole When two polar molecules connect

Dipole-Induced Dipole When a polar molecule gets near a non-polar one, it induces the non-polar one to become polar; thus, they connect

London Dispersion Instantaneous attraction for fractions of seconds in which non-polar molecules connect Very weak force

Predict & explain the MP trends of: 1) Li, Na, K, & Rb 2) F 2, Cl 2, Br 2, & I 2 3) LiF, NaCl, KBr, & RbI

Phase Diagram Graphic representation of all the phases of a substance with respect to temperature & pressure

1 atm 100 K400 K Approximate MP & BP:

Phase Diagrams

Describe conditions at each number

Define solids, liquids, gases, melting & Boiling points

Determine the phase changes for the 3 arrows:

PHASE DIAGRAM