Chapter 12 - Solids and Modern Materials

bonds

Solids are classified by the types of _____________ that hold the atoms in place.

Metallic Solids

Held together by a delocalized “sea” of shared valence electrons.

Ionic Solids

Held together by ionic bonds (coulombic/electrostatic attractions) between cations and anions.

Covalent Network Solids

Held together by an extended network of covalent bonds (multiple atoms of ONE element —> covalent bond)

Molecular Solids

Held together by relatively weak intermolecular forces.

Polymers

Long chains of atoms held together by covalent bonds (usually weak intermolecular forces).

Crystalline Solids

Atoms and ions arranged in an orderly (RIGID) repeating pattern.

get rid of electrons

Metallic Solids have positive charges because they would rather _______ ________ ___ ___________ to get to a full octet.

Crystalline

Ionic Solids (NaCl) and Covalent-network Solids (diamond) are both examples of what kind of structure?

[Consider Lattice structures…]

Amorphous Solids

Solids lacking an ordered structure.

Amorphous

Metallic Solids and Molecular Solids are examples of what structure?

Metallic bonding

_______________ _______________ results from delocalization of valence electrons throughout the solid.

amorphous

Metallic solids lack rigid structure, meaning they are…

Yes

Do metallic solids have properties similar to that of metals (i.e. malleable, ductile, conductivity).

Alloys

Substances containing more than one element and having the characteristic properties of metals.

One ALWAYS has to be a metal, the other(s) can be either.

different

Pure metals and alloys have different OR similar physical properties.

high

The ____________ melting and boiling points reflect the strength of the ionic bonds.

Substitutional Alloys

Substitute in an element with similar properties (same period, generally) → solute atoms take the positions normally occupied by a solvent atom.

Ex) One could substitute Ni for Cu in an alloy.

similar

Substitutional alloys must have ____________ atomic radii.

similar

Substitutional alloys must have ____________ bonding characteristics.

Interstitial Alloys

Solute occupies interstitial sites in the metallic lattice → One element (usually nonmetal) must have a SIGNIFICANTLY smaller radius than the other… in order to fit.

Ex) Steel (BIG Fe and small C)

increased bonding between metal and nonmetal

In Interstitial Alloys, why is the alloy much harder, stronger and less ductile than the pure metal?

Electron-Sea Model

Simple model that accounts for many properties of metals.

Electrons can flow freely through the model with no definite bonds, making the metals malleable/ductile as well as highly conductive.

charges, sizes

Strength of ionic bonds depends on the ___________ and __________ of the ions.

direct

Relationship between ionic bond strength and ion charge:

S+, C+

indirect

Relationship between ion size and ionic bond strength:

S+, S-

in water

When do Ionic Solids become good conductors?

(Consider dissociation capabilities → ion-dipole bonding…)

charge

Does charge or size take priority in determining the Ionic Bond strength?

electrical insulators

Valence electrons in ionic compounds are confined to the anions, rather than delocalized. Por eso, ionic solids tend to be ______________ _______________.

brittle

Stress applied to an ionic solid may shift the alignment of ions and create repulsive interactions between ions of like charge.

This is result of ionic solids being generally ______________.

low

Molecular Solids have _________ melting points due to the weak intermolecular forces holding them together.

soft

Are molecular solids hard or soft?

London Dispersion, Dipole-Dipole, Hydrogen Bonding

Types of intermolecular forces found in Molecular Solids:

gases, liquids

Molecular solids are often _______ or ___________ at room temperature.

poor

Molecular solids show _________ thermal and electrical conductivity.

higher, harder

Covalent-network Solids have ___________ melting/boiling points and are __________ than molecular solids.

(Consequence of the strong covalent bonds that connect the atoms.)

Diamond

_______________ is a large molecule held together by covalent bonds (Covalent-network).