Chapter 21 Review

Video Review

Key Concept Summary

TA Summary


Property of absorbing photons throughout the electromagnetic spectrum.
How easily light bounces off the surface of a substance.
A set of molecular orbitals so tightly spaced that the energies overlap each other.
Metal-metal compound.
An electron which is not focused around any one nucleus.
The degree to which a substance conducts heat.
Positive nuclei surrounded by a "sea" of electrons.
Substances that conduct electricity better than insulators but not as good as conductors.
The ability of atoms to change relative position without weakening the bonds between them.
A measure for how difficult it is to make a current move through a substance.


Light can only be seen through metal that is so thin it is only a few atoms thick.
Bonding MOs have electron energies that are lower than electron energies for unbound valence electrons.
Compositions of alloys are generally fixed in simple ratios.
For an alloy to form, the atoms must be different sizes.
Often alloys are better conductors than either of the metals, in their pure form, that make up the alloy.
Metals conduct better at higher temperatures.
Semiconductors conduct better at higher temperatures.
Metals do not have a band gap.
Metals have a greater tendency than non-metals to lose electrons.
Metals have higher ionization energies than non-metals do.
The energies of the orbitals that form when metals interact are very widely spaced in energy.
Metals do not let light through.

Analysis Questions

Which of the following pairs of metal is most likely to form alloys of all compositions?
Which of the following pairs of metals is most likely to form alloys of all proportions?
Which of the following is NOT why alloys are useful to us today? (Which of the following is false.)
How do semiconductors change with increasing temperatures?
Compounds between two different metals are called
If a certain LED (doped semi-conductor) is cooled in liquid nitrogen, the color moves to a higher frequency. What happens to the band gap?
Locate the elements palladium (Pd, atomic #46) and nickel (Ni, atomic #28) on the periodic table. If Pd is combined with Ni, which of the following characteristics will the product show at room temperature?
Which of the following is NOT a characteristic of a metal or alloy?
Which of the following is a correct comparison of metals and semi-conductors?
A metal can best be described as which of the following?

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