Editing Group 8 element (section)

{{Short description|Group of chemical elements in the periodic table}}
{{Infobox periodic table group
| title       = Group&nbsp;8 {{nowrap|in the periodic table}}
| group number= 8
| trivial name= 
| by element  = iron group ([[iron group|nonstandard]])
| CAS         = part of VIIIB
| old IUPAC   = part of VIII
| mark        = Fe,Ru,Os,Hs
| left        = [[Group 7 element|group 7]]
| right       = [[Group 9 element|group 9]]
}}
{| class="floatright"
! colspan=2 style="text-align:left;" | ↓&nbsp;<small>[[Period (periodic table)|Period]]</small>
|-
! [[Period 4 element|4]]
| {{element cell image|26|Iron|Fe| |Solid|Transition metal|Primordial|image=Iron electrolytic and 1cm3 cube.jpg|image caption=Iron, electrolytic made, 99,97%+}}
|-
! [[Period 5 element|5]]
| {{element cell image|44|Ruthenium|Ru| |Solid|Transition metal|Primordial|image=Ruthenium a half bar.jpg|image caption=Ruthenium bar, 99,99%}}
|-
! [[Period 6 element|6]]
| {{element cell image|76|Osmium|Os| |Solid|Transition metal|Primordial|image=Osmium-crystals 2.jpg|image caption=Osmium crystals, ≈99,99%}}
|-
! [[Period 7 element|7]]
| {{element cell image|108|Hassium|Hs| |Unknown phase|Transition metal|Synthetic}}
|-
| colspan="2"|
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''Legend''
{| style="text-align:center; border:0; margin:1em auto;"
|-
| style="border:{{element color|Primordial}}; background:{{Element color|table mark}}; padding:0 2px;" | [[primordial element]]
|-
| style="border:{{element color|Synthetic}}; background:{{Element color|table mark}}; padding:0 2px;" | [[synthetic element]]
|}
|}

'''Group 8''' is a [[group (periodic table)|group]] (column) of [[chemical element]]s in the [[periodic table]]. It consists of [[iron]] (Fe), [[ruthenium]] (Ru), [[osmium]] (Os) and [[hassium]] (Hs).<ref name=leigh>{{Cite book |last=Leigh |first=Geoffrey J. |title=Nomenclature of inorganic chemistry: recommendations 1990 |date=1990 |publisher=Blackwell scientific publ |others=Union internationale de chimie pure et appliquée |isbn=978-0-632-02494-0 |location=Oxford London Edinburgh}}</ref> "Group 8" is the modern standard designation for this group, adopted by the [[IUPAC]] in 1990.<ref name=leigh/> It should not be confused with "group VIIIA" in the CAS system, which is group 18 (current IUPAC), the [[noble gas]]es. In the [[Group (periodic table)|older group naming systems]], this group was combined with groups [[group 9 element|9]] and [[group 10 element|10]] and called group "VIIIB" in the [[Chemical Abstracts Service]] (CAS) "U.S. system", or "VIII" in the old IUPAC (pre-1990) "European system" (and in [[Mendeleev]]'s original table). The elements in this group are all [[transition metal]]s that lie in the [[d-block]] of the periodic table.

While groups (columns) of the periodic table are usually named after their lightest member (as in "the oxygen group" for group 16), [[iron group]] has  historically been used differently; most often, it means a set of adjacent elements on [[period 4 element|period (row) 4]] of the table that includes iron, such as [[chromium]], [[manganese]], [[iron]], [[cobalt]], and [[nickel]], or only the last three, or some other set, depending on the context.

Like other groups, the members of this family show patterns in [[electron configuration]], especially in the outermost shells, resulting in trends in chemical behavior.