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{{lowercase|s-block}}

{| align="right" style="margin:0 0 1em 1em;"
|+ '''Chemical elements in s-block'''
|-
! [[Periodic table group|Group]]
! [[Alkali metal       |1]]
! [[Alkaline earth metal|2]]
! [[Noble gas|18]]
|-
! [[Periodic table period|Period]]
|
|
|
|-
! [[Period 1 element|1]]
| {{element cell| 1|Hydrogen|H| |Gas|Nonmetals|Primordial}}
|
| {{element cell| 2|Helium|He| |Gas|Noble gases|Primordial}}
|-
! [[Period 2 element|2]]
| {{element cell| 3|Lithium|Li| |Solid|Alkali metals|Primordial}}
| {{element cell| 4|Beryllium|Be| |Solid|Alkaline earth metals|Primordial}}
|
|-
! [[Period 3 element|3]]
| {{element cell|11|Sodium|Na| |Solid|Alkali metals|Primordial}}
| {{element cell|12|Magnesium|Mg| |Solid|Alkaline earth metals|Primordial}}
|
|-
! [[Period 4 element|4]]
| {{element cell|19|Potassium|K| |Solid|Alkali metals|Primordial}}
| {{element cell|20|Calcium|Ca| |Solid|Alkaline earth metals|Primordial}}
|
|-
! [[Period 5 element|5]]
| {{element cell|37|Rubidium|Rb| |Solid|Alkali metals|Primordial}}
| {{element cell|38|Strontium|Sr| |Solid|Alkaline earth metals|Primordial}}
|
|-
! [[Period 6 element|6]]
| {{element cell|55|Caesium|Cs| |Solid|Alkali metals|Primordial}}
| {{element cell|56|Barium|Ba| |Solid|Alkaline earth metals|Primordial}}
|
|-
! [[Period 7 element|7]]
| {{element cell|87|Francium|Fr| |Solid|Alkali metals|Natural radio}}
| {{element cell|88|Radium|Ra| |Solid|Alkaline earth metals|Natural radio}}
|
|}
The '''s-block''' of the [[Periodic table (extended)|periodic table]] of [[Chemical element|elements]] consists of the first two [[periodic table group|group]]s: the [[alkali metals]] and [[alkaline earth metals]], plus [[hydrogen]] and [[helium]].  

These elements are distinguished by the property that in the atomic [[ground state]], the highest-energy [[electron]] is in an s-[[atomic orbital|orbital]].  Except in hydrogen and helium, these electrons are very easily lost to form positive [[ion]]s. The helium configuration is chemically exceedingly stable and thus helium has ''no known stable compounds''; thus it is generally grouped with the [[noble gases]].

The other elements of the s-block are all extremely powerful [[reducing agent]]s, so much so that they ''never'' occur naturally in the free state. The metallic forms of these elements can only be extracted by [[electrolysis]] of a molten salt, since [[water]] is much more easily reduced to hydrogen than the ions of these metals. [[Sir Humphry Davy]], in [[1807]] and [[1808]], was the first to isolate all of these metals except [[lithium]], [[beryllium]], [[rubidium]] and [[caesium]]. Beryllium was isolated independently by F. Wooler and A.A. Bussy in [[1828]], whilst lithium was isolated by [[Robert Bunsen]] in [[1854]], who isolated rubidium nine years later after having observed it and caesium spectroscopically. Caesium was not isolated until [[1881]] when [[Carl Setterberg]] electrolysed the molten [[cyanide]].

The s-block metals vary from extremely soft (all the alkali metals) to quite hard (beryllium). With the exception of beryllium and magnesium, the metals are too reactive for any structural use except as very minor components (<2%) of alloys with [[lead]]. Beryllium and magnesium, though very expensive, are valuable for uses that require strength and lightness. They are extremely valuable as reducing agents to extract [[titanium]], [[zirconium]], [[thorium]] and [[tantalum]] from their ores, and have other uses as reducing agents in [[organic chemistry]].

All the s-block metals are dangerous [[fire]] hazards which require special extinguishants to extinguish. Except for beryllium and magnesium, storage must be under either [[argon]] or an inert liquid [[hydrocarbon]]. They react vigorously with [[water]] to liberate hydrogen, except for magnesium, which reacts slowly, and beryllium, which reacts only when amalgamated with [[mercury (element)|mercury]] to destroy the [[oxide]] film. Lithium has similar properties to magnesium due to the diagonal relationship with magnesium in the periodic table.

==See also==

* [[Electron configuration]]

{{PeriodicTablesFooter}} [[Category:Periodic table]] <br/>

[[Category:Chemical element groups]]

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