Solids The Neglected “State” Of Chemistry

Material Science

Types of matter: element, compound, mixture   Types of matter: element, compound, mixture Types of elements: metals, nonmetals, semimetals Types of structure: crystalline, amorphous Types of bonding: metallic, ionic, covalent, intermolecular forces metals ceramics/glass polymers metallic elements metals & nonmetals or nonmetals semimetals & nonmetals element or mixture compound or mixture of mostly compounds compounds crystalline ceramics = crystalline mostly amorphous w/ glass = amorphous regions of crystallinity metallic bonding ionic bonding and covalent bonding with network covalent bonding weak intermolecular forces

Types of Bonding Type of bonding Metallic Ionic Covalent Intermolecular Forces Type of elements involved Between Metals Between Metals and Nonmetals Between Nonmetals Between Molecules Givers & or takers of electrons Between givers Between givers and takers Between takers Description Valence e- roam freely between many atoms. Sea of electrons Transfer e- Makes (+) and (-) ions that are attracted to each other Share e- Forms discrete molecules Hold covalently bonded molecules together as a solid Type of material formed Solid metals and alloys Ceramics and glass Polymers and some ceramics/glasses Helps form solid polymers Strength of bond Relatively strong Very strong Weak Properties produced Good conductors, workable, corrode easily Brittle, hard, high melt temps, nonconductors as solids, don’t corrode Insulators, don’t corrode Help determine a lot of properties of covalent compounds (polymers)

amorphous crystalline

Hexagonal close packed Simple cubic Face-centered cubic (FCC) Body-centered cubic (BCC) Hexagonal close packed (HCP)

Most Common Metal Crystal Structures BCC Body Centered Cubic FCC Face Centered Cubic HCP Hexagonal Close Pack Over heads of pennys BB Board

BCC simple cubic FCC HCP

BCC Body-centered cubic FCC Face-centered cubic

Type of crystal structure Workability Which crystal structure is more workable? Many slip planes or few slip planes? Tightly packed or loosely packed? (more or less “gappiness”?) Ice cube tray demo Type of crystal structure Closely packed? Many slip planes? Workability FCC BCC HCP

Type of crystal structure Closely packed? Many slip planes? Workability FCC Yes Highest BCC No Medium HCP Lowest

Crystal Structures & Metals BCC FCC HCP Other Chromium Aluminum Cobalt Manganese Iron (<912°C) Calcium Magnesium Tin Molybdenum Copper Titanium Sodium Gold Zinc Tungsten Iron (>912°C) Lead Nickel Platinum Silver

Cubic Face Centered Cubic Body Centered Cubic

Thermal Shock Demo Types of glass soda-lime glass borosilicate glass fused silica glass

Types of Glass Soda Lime glass (cheap) windows 1285f 696c Softening temp Soda Lime glass (cheap) windows 1285f 696c Borosilicate (better) beakers 1436f 780c 96% Silica (better) 2886f 1586c Fused Silica (best) 2876f 1580c

Coefficient of Thermal Expansion Thermal Shock Material Coefficient of Thermal Expansion Fused Silica Glass (cm/cm x °C) Borosilicate Glass 6 X 10-7 Aluminosilicate Glass 33 X 10-7 Porcelain 44 X 10-7 Soda-Lime Glass 60 X 10-7 Mild Steel 85 x 10-7 Aluminum 110 X 10-7  

Category Purpose Metal oxides Glass former Modifier Intermediate Gives atomic structure – makes up backbone of network solid SiO2 (silica) - primary Also oxides of: B, Ge, P, As, V Modifier Lower melt temp, Makes it easier to work w/ Oxides of alkali metals *(Na2O & K2O) and alkaline earth metals **(CaO & MgO) Intermediate Acts as either former or modifier based on other ingredients present Oxides of: Al, Sb, Pb, Zn, and sometimes B *make it chemically less stable **restore some stability

Glass type Ingredients Uses Advantages Disadvantages Soda-lime (flint) (most common) Silica (SiO2) Soda (Na2O) Lime (CaO) Windows, bottles, etc. Low price, Forms shapes easily Low thermal shock resistance Borosilicate Alumina (Al2O3) Boron oxide (B2O3) Lab glassware Cookware Lamp bulbs (Pyrex) Withstands thermal shock better and higher temps More expensive, Harder to work Lead-alkali (lead crystal) Sodium oxide Lead oxide Art glass, Expensive glassware Sparkle, High electrical resistance Toxicity, Doesn’t w/stand thermal shock or high temp