7 Written questions
6 Multiple choice questions
- Very Low: due to the strong Coulombic interactions of positive and negative ions arranged in a regular three-dimensional array.
- Malleable and ductile: deforming the solid does not change the environment immediately surrounding each metal core
- 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
- Poor: ionic lattices are rigid and once broken tend to cleave along an entire plane.
- Good: alloys usually retain a sea of mobile electrons (delocalized covalent bonds) and so remain conducting (for both HEAT and ELECTRICITY)
- Non-conductive (insulators): ions are pinned by the rigid lattice.
6 True/False questions
Substitutional Alloy (definition) → formed between atoms of comparable radius, where one atom substitutes for the other in the lattice
Non-polar solubility of an ionic solid → Soluble: the charged ions interact with the dipoles on the water molecules.
Brittleness of an ionic solid → Hard: ionic lattice is strong and rigid
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) → 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.
Water 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.