Metals are one common type of solids. Our model for
metals is a bunch of positive cations in a regular, repeating lattice much like
a crystal with a "sea" of loosely bound electrons surrounding them. Common
properties of metals include:
- High electrical conductivity. The electrons in a metal can move easily,
thus conducting electricity.
- High thermal conductivity. Heat is carried in metals through collisions
between electrons, which occur easily since they are not tightly bound by the
ions.
- Ductility. Metals can easily be bent or hammered into shape. The ions are
not fixed into placed with strong, directional bonds like in a network
covalent solid, and thus the metal can be easily deformed.
- Luster. In atoms or small molecules, the electrons can only reside in a
few distinct energy states, (Such as a 3d orbital or a sigma bonding orbital.)
and thus give off a line spectrum as electrons move from energy level to
energy level. In metals, the "sea" of electrons has a very large number of
possible energy levels, and thus metals can absorb and emit light at a large
number of frequencies.
- Insoluble in most solvents. Electrons cannot easily go into solution, and
the ions cannot dissolve by themselves.
Most elements towards the lower left of the periodic table are metals, such
as sodium, iron, nickel and gold.
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