Very Low: due to the strong Coulombic interactions of positive and negative ions arranged in a regular three-dimensional array.
Brittleness of an ionic solid
Brittle: due to the repulsion of like charges caused when one layer slides across another layer.
Conductivity of an ionic solid
Non-conductive (insulators): ions are pinned by the rigid lattice.
Identification of an ionic solid
Unable to conduct electricity as a solid; soluble in water; aqueous solution conducts electricity
Water solubility of an ionic solid
Soluble: the charged ions interact with the dipoles on the water molecules.
Non-polar solubility of an ionic solid
Insoluble: ionic compounds tend not to dissolve in nonpolar solvents because the attractions between ions are much more favorable than the attractions among the separated ions and nonpolar solvent molecules.
Malleability and ductility of an ionic solid
Poor: ionic lattices are rigid and once broken tend to cleave along an entire plane.
Hardness of an ionic solid
Hard: ionic lattice is strong and rigid
Conductivity of a metallic solid
Good: electrons are delocalized and relatively free to move
Malleability and ductility of a metallic solid
Malleable and ductile: deforming the solid does not change the environment immediately surrounding each metal core
Interstitial Alloy (definition)
formed between atoms of different radius, where the smaller atoms fill the interstitial spaces between the larger atoms
Interstitial Alloy (properties)
interstitial atoms do not appreciably expand the lattice and so density is often substantially increased; interstitial atoms make the lattice more rigid reducing ductility and malleability
Substitutional Alloy (definition)
formed between atoms of comparable radius, where one atom substitutes for the other in the lattice
Substitutional Alloy (properties)
density is usually between that of the component metals; alloy remains malleable and ductile
Conductivity of alloys
Good: alloys usually retain a sea of mobile electrons (delocalized covalent bonds) and so remain conducting (for both HEAT and ELECTRICITY)
Surface chemistry of an alloy
Alloy formation sometimes alters the chemistry such as the formation of a chemically inert oxide layer in stainless steel.
Optical properties of metals (list and reason)
Shiny, reflective, lustrous: because electrons move freely throughout the metal. Metals are shiny because of the very strong absorption of light by the delocalised bonding electrons.
Optical properties of metal (explained)
When light falls on a metal it is almost totally absorbed since the bonding electrons can jump up to a broad band of energy levels allowing energy changes corresponding to the full range of frequencies in the visible region of the spectrum.
These currents immediately re-emit the light out of the metal thus providing a strong reflection if the metal surface is smooth.