Chemistry Reference
In-Depth Information
TABLE 2.1
Some Physical and Chemical Properties of Metals, Nonmetals, and Metalloids
Metals
Metalloids
Nonmetals
Opaque with a metallic luster
Metallic luster
No luster
Solid at room temperature (Hg is liquid)
Solid at room temperature
Gases, liquids, or solids
High thermal conductivity
Good thermal conductivity
Good thermal isolators
(excepting C in diamond)
High electrical conductivity
Good electrical
conductivity
Poor electrical conductivity
(excepting C in graphite)
Malleable and ductile
Brittle
Brittle (when solid)
Metallic bonding; closed packed crystal
structures, high coordination numbers
Relatively open crystal
structures, medium
coordination numbers
Weak molecular forces, low
coordination numbers
Oxidation numbers of metals in
compounds are positive
Oxidation numbers in
compounds are positive
or negative
Oxidation numbers in
compounds are positive or
negative
In solution they tend to lose electrons to
form positive ions
They form cations and
anions
Tend to gain electrons and
form negative ions
Low ionization energy
Intermediate ionization
energies
High ionization energy
Low electronegativity
Electronegativity values:
from 1.9 to 2.4
High electronegativity
They form ionic compounds
with nonmetals
They tend to form covalent
bonds in compounds
They form ionic
compounds with metals
and covalent compounds
with other nonmetals
metals as compared to nonmetals is a consequence of the tight metallic packing in
the metal crystal structures. The strongest attractive force between atoms in metals
can be found in the middle of the transition metals series, in elements where the
delocalization of electrons is strongest. Metals that have density values higher than
5 g/cm
3
are called
heavy metals
. However, this term has been used for a variety of
transition metals in various biological studies, leading to contradictory definitions
and the proposal to abandon its use (for example, Nieboer and Richardson 1980;
Phipps 1980; Borovik 1990; Duffus 2002).
2.3 CHARACTERIZATION OF METALS ACCORDING
TO THEIR ELECTRONIC CONFIGURATION
The physical and chemical properties of the chemical elements are a consequence
of their electronic structure. The chemistry of metals and of their compounds
show the existence of analogies for metals that have to fill s, p, d, or f subshells.
Therefore, those elements that have the same value of the second quantum number
(l) (see Section 2.3.1) are classified in the s, p, d, f blocks of elements (
Figure 2.2
).
