Metals are located on the left and middle sections of the periodic table. Group IA and IIA are the alkali metals and are the most active, while the transition elements found in Groups IB to VIIIB are less active, but also considered metals. Except for Mercury, metals are solids at room temperature and have high melting points and densities. The properties of metals are due to how easily the electrons in the valence shell of metal atoms can be removed. These common properties are:
– Shiny appearance
– Solid at room temperature (excluding Mercury)
– High melting point
– High density
– Large atomic radius
– Low ionization energy
– Low electronegativity
– A common high deformation
– Thermal conductor
– Electrical conductor
Group IA consists of the alkali metals which exhibit many of the common physical properties of metals even though their densities are lower than other metals. Because of their low ionization energies, they have high metallic properties and are also high reactivity. The second group, IIA, consists of the alkaline earth metals, which also have properties in common with metals but, like alkali metals, are also not found in elemental form in nature.
Groups IB through VIIIB are called the transition metals. Like all metals, they are good electrical conductors, conduct heat well, and are malleable and ductile. An important note is that their valence electrons, the electrons used to combine with other elemental atoms, are present on more than one shell giving them the ability to exhibit several different oxidation states. Also important to remember is that iron, cobalt and nickel are the only elements known with the ability to produce a magnetic field.
While not confined to one group because of characteristics such as electron count and weight, Aluminum, Gallium, Indium, Tin, Thallium, Lead and Bismuth are referred to as the “Other Metals”. They are unlike other metals in that they do not exhibit different oxidation states, are solid and have a relatively high density.
Though there are other groups called “Metalloids” and “Non-metals” that do exhibit properties of both metals and non-metals such as conductivity, their similarities end there and eliminate them from consideration as actual metals.
Sources – wikipedia.com, about.com, chemicalelements.com