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.
Most elements are metals. This group includes the alkali metals, alkaline earth metals, transition metals, basic metals, lanthanides (rare earth elements), and actinides. Although separate on the periodic table, the lanthanides and actinides are really specific types of transition metals. Here's a list of all the elements on the periodic table that are metals: Alkali Metals