2.3/2.4 Structure of Ionic Solids / Structures of Metals and Alloys

What are the 4 different types of bonding in solids?

Ionic,metallic, covalent network, and molecular

What is a crystal lattice?

A systematic, 3-D array that maximizes attractions and minimizes repulsions

What are the properties of crystalline solids?

Brittle bc when pressure is put onto one side, the ions can shift and align (+ with + and - with -), causing them to repel

Properties of ionic solids (vapor pressure/MP/cond)

Low vapor pressure, high MP, conductive in water only (bc ions are mobile)

What is a network covalent solid?

Atoms are bonded in a 3-D lattice or layers of 2-D networks where covalent bonds are spread throughout the entire structure (strong bonds)

Properties of network covalent solids (vapor pressure/MP/cond)

low vapor pressure, high MP, conductivity depends on molecule

What are the 6 common network covalent solids?

Diamond(tetrahedral), graphite(2D network layers), silicon dioxide(tetrahedral), silicon carbide(tetrahedral), boron nitride, boron carbide

What is a molecular solid?

Molecules bonded through IMFs (LDF/DpDp/H-bond)

What are the properties of molecular solids? (vapor pressure/MP/cond)

high vapor pressure, low MP, and low cond bc electrons are not free-moving

What is a metallic solid?

Nonmetal + metalloid bonded covalently. Forms a lattice with delocalized electrons

What are the properties of metallic solids? (vapor pressure/MP/cond)

low vapor pressure, high MP, high cond (sea of electrons are free moving and can carry a charge). They’re also malleable and ductile bc the sea of electrons act as a flexible glue, allowing ions to slide past one another without creating repulsions

What is an alloy?

Combinations of two or more elements (usually metals)

What are the properties of alloys?

Typically stronger than pure metals, good conductors (retains a sea of electrons)

What is a substitutional alloy?

Element A replaces B

What is an interstitial alloy? What is significant about interstitial alloys?

Element C(smaller) fills space between A and B. This makes the lattice more rigid, decreasing malleability/ductility and making it more brittle