The common characteristics that characterize metals are:
- They have metal gloss. That is, the ability to reflect light (shine) when polished or trimmed.
- They are good heat and power conductors.
- They form positive ions under conditions that are not extreme.
- They are solid at room temperature with the exception of mercury (Hg) melting at -38.8 ° C.
Elements that do not have these properties are called non-metals. However, a small group of elements have both metallic properties and some non-metallic properties, and the group is therefore called semi-metals.
The heavy metals are comprised of metals with a ‘high density’. There is no unambiguous definition, but the limit is typically iron with a density of 7.9 g/cm3. Therefore, lead (Pb), gold (Au) and copper are considered as heavy metals.
Similarly, the light metals are those metals that have a relatively low density. However, it is not a name in academic terminology. The most famous metals in this group are aluminum and magnesium.
The precious metals are defined as the metals that appear to the right of the dihydrogen in the stress line . The precious metals are characterized by being less reactive, and therefore do not form chemical compounds. Most famous examples of precious metals are gold (Au), silver (Ag) and platinum (Pt).