Editing Period 1 element (section)

==Periodic trends==
All other periods in the periodic table contain at least eight elements, and it is often helpful to consider [[periodic trends]] across the period. However, period&nbsp;1 contains only two elements, so this concept does not apply here.{{fact|date=August 2019}}

In terms of vertical trends down groups, helium can be seen as a typical [[noble gas]] at the head of the IUPAC [[group&nbsp;18]], but as discussed below, hydrogen's chemistry is unique and it is not easily assigned to any group.<ref>{{cite journal|title=Where to Put Hydrogen in a Periodic Table?|journal=Foundations of Chemistry|year=2006|author=Michael Laing|doi=10.1007/s10698-006-9027-5|volume=9|issue=2|pages=127–137|s2cid=93781427 }}</ref>