It has long been presumed that there is a common cause at the genetic, cognitive, and neural levels for autism's characteristic triad of symptoms. However, there is increasing suspicion that autism is instead a complex disorder whose core aspects have distinct causes that often co-occur.
1 Transition metals are kinds of metals that have electrons in d or f orbitals. 2  Transition metals are in columns 3-12 of the periodic table and in the lanthanide and actinide series.  Most transition metals are lustrous, silvery, hard, and good conductors; however, properties may vary greatly.
The periodic table is a chart that shows how elements are related to one another. Indium is a transition metal that is also part of the platinum family. The metals in the platinum family are also known as the noble metals. They have this name because they do not react well with other elements and compounds. They appear to be too superior to react with most other substances. In fact, iridium is the most corrosion-resistant metal known.