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.
Best Answer: Look at the periodic table of elements. alkali metals are the ones in Group 1: Li, Na,K, etc. side note: (they must give away 1 electron to be perfect) transition metal are from group 3 to group 12. side note: (most of them have many different charges on the periodic table and also, transition metals have color while the others don't) halogens are group 17.