Solids Properties Flashcards
What is an amorphous solid?
An irregular solid composed of a non-uniform network of particles
What forces hold an amorphous solid together?
Directional covalent bonds
Provide examples of an amorphous solid:
Glass, rubber, some plastics
What is the hardness of an amorphous solid?
Variable (non-regular bonds, not predictable between solids)
What is the melting point of an amorphous solid?
Variable (non-regular bonds, melt at different temperatures)
Are amorphous solids conductors?
Poor conductors
What is a crystalline solid?
Solid that shows an ordered repeating particle pattern (true solid)
What is an atomic solid?
A solid in which atoms (can be of varying elements) occupy positions within a crystalline structure.
What is a (covalent) network solid?
A solid composed of repeating covalently bonded atoms.
What bonds hold a network solid together?
Directional covalent bonds
Provide examples of a network solid:
Diamond (3D), graphite (2D), quartz (SiO2)
What are the structural units of a network solid?
Atoms (typically nonmetals)
What is the hardness of a network solid?
Usually high, but variable
What is the melting point of a network solid?
Usually high, but variable
Are network solids conductors?
No, insulators
Which is stronger, a 2D or 3D network solid?
3D (also has a higher melting point and hardness e.g. diamond vs. graphite)
What is a unit cell?
The simplest repeating part of a crystal
What is a metallic solid?
A solid composed of metal atoms in a sea of electrons
What forces hold a metallic solid together?
Nondirectional covalent bonds (delocalized valence electrons)
Provide examples of a metallic solid:
Iron, Gold, Copper, Steel, Pewter
What is an interstitial alloy?
A metallic alloy in which other atoms are placed into the open spaces between metal cations (e.g. carbon in steel)
What is a substitutional alloy?
A metallic alloy in which other metallic atoms are introduced into the electron sea (e.g. brass)
What are the structural units of a metallic solid?
Metal ions (cations)
What is the hardness of a metallic solid?
Alloys (hard)
Pure (soft)
What is the melting point of a metallic solid?
Variable, can be incredibly hot (e.g. Tungsten W)
Are metallic solids conductors?
Very good conductors of both heat and electricity.
What is a group 8A solid?
Solids composed of elements from the noble gases
Provide examples of a group 8A solid:
Argon (s)
What are the forces holding a group 8A solid together?
London dispersion forces (LDFs)
What is the hardness of a group 8A solid?
Soft
What is the melting point of a group 8A solid?
Very low
What is a molecular solid?
Molecules held in a crystal lattice
What forces hold a molecular solid together?
LDFs, dip/dip (sometimes), H-bond (sometimes)
Provide examples of a molecular solid:
Ice, dry ice, sugars, O2, NH3, etc.
What are the structural units of a molecular solid?
Discrete molecules
What is the hardness of a molecular solid?
Soft
What is the melting point of a molecular solid?
Low (variable)
Are molecular solids conductors?
Poor conductors
What is an ionic solid?
A crystal lattice of ions
What forces hold an ionic solid together?
Ionic/electrostatic forces
Provide examples of an ionic solid:
NaCl, MgO, CaCl2, K2SO4
What are the structural units of an ionic solid?
Unit cells of cations and anions
What is the hardness of an ionic solid?
Hard but brittle
What is the melting point of ionic solids?
Very high
What is the solubility of ionic solids?
Usually soluble in water
Are ionic solids conductors?
Conductors in liquid phase, non conductors in solid phase
