Editing Reactivity series (section)

== Comparison with standard electrode potentials ==
The reactivity series is sometimes quoted in the strict reverse order of [[standard electrode potential]]s, when it is also known as the "[[electrochemical series]]".<ref>{{Webarchive|url=https://web.archive.org/web/20220224075029/https://www.primefan.ru/stuff/chem/back2019.png|date=20220224|title=Periodic table poster}} by A. V. Kulsha and T. A. Kolevich gives: {{cquote|[[lithium|Li]] > [[caesium|Cs]] > [[rubidium|Rb]] > [[potassium|K]] > [[barium|Ba]] > [[strontium|Sr]] > [[calcium|Ca]] > [[sodium|Na]] > [[lanthanum|La]] > [[yttrium|Y]] > [[magnesium|Mg]] > [[cerium|Ce]] > [[scandium|Sc]] > [[beryllium|Be]] > [[aluminium|Al]] > [[titanium|Ti]] > [[manganese|Mn]] > [[vanadium|V]] > [[chromium|Cr]] > [[zinc|Zn]] > [[gallium|Ga]] > [[iron|Fe]] > [[cadmium|Cd]] > [[indium|In]] > [[thallium|Tl]] > [[cobalt|Co]] > [[nickel|Ni]] > [[tin|Sn]] > [[lead|Pb]] > ([[hydrogen|H]]) > [[antimony|Sb]] > [[bismuth|Bi]] > [[copper|Cu]] > [[polonium|Po]] > [[ruthenium|Ru]] > [[rhodium|Rh]] > [[silver|Ag]] > [[mercury (element)|Hg]] > [[palladium|Pd]] > [[iridium|Ir]] > [[platinum|Pt]] > [[gold|Au]]}}</ref>

The following list includes the metallic elements of the first six periods. It is mostly based on tables provided by [[NIST]].<ref>[https://www.nist.gov/system/files/documents/2019/04/02/jpcrd355.pdf Standard Electrode Potentials and Temperature Coefficients in Water at 298.15 K], Steven G. Bratsch (NIST)</ref><ref>For antimony: [http://www.dactari.toxcea.org/Local/dactari/dir/pdf/default/Sb.pdf Antimony - Physico-chemical properties - DACTARI]</ref> However, not all sources give the same values: there are some differences between the precise values given by NIST and the [[CRC Handbook of Chemistry and Physics]]. In the first six periods this does not make a difference to the relative order, but in the seventh period it does, so the seventh-period elements have been excluded. (In any case, the typical oxidation states for the most accessible seventh-period elements [[thorium]] and [[uranium]] are too high to allow a direct comparison.)<ref name="CRC">{{RubberBible87th}}</ref>

Hydrogen has been included as a benchmark, although it is not a metal. Borderline [[germanium]], [[antimony]], and [[astatine]] have been included. Some other elements in the middle of the 4d and 5d rows have been omitted (Zr–Tc, Hf–Os) when their simple cations are too highly charged or of rather doubtful existence. Greyed-out rows indicate values based on estimation rather than experiment.
{| class="wikitable"
|-
! ''[[Atomic number|Z]]''
! Sym
! Element
! Reaction
! E° (V)
|-
| 3
| Li
| [[lithium]]
| Li<sup>+</sup> + e<sup>−</sup> → Li
| −3.04
|-
| 55
| Cs
| [[caesium]]
| Cs<sup>+</sup> + e<sup>−</sup> → Cs
| −3.03
|-
| 37
| Rb
| [[rubidium]]
| Rb<sup>+</sup> + e<sup>−</sup> → Rb
| −2.94
|-
| 19
| K
| [[potassium]]
| K<sup>+</sup> + e<sup>−</sup> → K
| −2.94
|-
| 56
| Ba
| [[barium]]
| Ba<sup>2+</sup> + 2 e<sup>−</sup> → Ba
| −2.91
|-
| 38
| Sr
| [[strontium]]
| Sr<sup>2+</sup> + 2 e<sup>−</sup> → Sr
| −2.90
|-
| 20
| Ca
| [[calcium]]
| Ca<sup>2+</sup> + 2 e<sup>−</sup> → Ca
| −2.87
|-
| 11
| Na
| [[sodium]]
| Na<sup>+</sup> + e<sup>−</sup> → Na
| −2.71
|-
| 57
| La
| [[lanthanum]]
| La<sup>3+</sup> + 3 e<sup>−</sup> → La
| −2.38
|-
| 39
| Y
| [[yttrium]]
| Y<sup>3+</sup> + 3 e<sup>−</sup> → Y
| −2.38
|-
| 12
| Mg
| [[magnesium]]
| Mg<sup>2+</sup> + 2 e<sup>−</sup> → Mg
| −2.36
|-
| 59
| Pr
| [[praseodymium]]
| Pr<sup>3+</sup> + 3 e<sup>−</sup> → Pr
| −2.35
|-
| 58
| Ce
| [[cerium]]
| Ce<sup>3+</sup> + 3 e<sup>−</sup> → Ce
| −2.34
|-
| 68
| Er
| [[erbium]]
| Er<sup>3+</sup> + 3 e<sup>−</sup> → Er
| −2.33
|-
| 67
| Ho
| [[holmium]]
| Ho<sup>3+</sup> + 3 e<sup>−</sup> → Ho
| −2.33
|-
| 60
| Nd
| [[neodymium]]
| Nd<sup>3+</sup> + 3 e<sup>−</sup> → Nd
| −2.32
|-
| 69
| Tm
| [[thulium]]
| Tm<sup>3+</sup> + 3 e<sup>−</sup> → Tm
| −2.32
|-
| 62
| Sm
| [[samarium]]
| Sm<sup>3+</sup> + 3 e<sup>−</sup> → Sm
| −2.30
|- bgcolor=#e8e8e8
| 61
| Pm
| [[promethium]]
| Pm<sup>3+</sup> + 3 e<sup>−</sup> → Pm
| −2.30
|-
| 66
| Dy
| [[dysprosium]]
| Dy<sup>3+</sup> + 3 e<sup>−</sup> → Dy
| −2.29
|-
| 71
| Lu
| [[lutetium]]
| Lu<sup>3+</sup> + 3 e<sup>−</sup> → Lu
| −2.28
|-
| 65
| Tb
| [[terbium]]
| Tb<sup>3+</sup> + 3 e<sup>−</sup> → Tb
| −2.28
|-
| 64
| Gd
| [[gadolinium]]
| Gd<sup>3+</sup> + 3 e<sup>−</sup> → Gd
| −2.28
|-
| 70
| Yb
| [[ytterbium]]
| Yb<sup>3+</sup> + 3 e<sup>−</sup> → Yb
| −2.19
|-
| 21
| Sc
| [[scandium]]
| Sc<sup>3+</sup> + 3 e<sup>−</sup> → Sc
| −2.09
|-
| 63
| Eu
| [[europium]]
| Eu<sup>3+</sup> + 3 e<sup>−</sup> → Eu
| −1.99
|-
| 4
| Be
| [[beryllium]]
| Be<sup>2+</sup> + 2 e<sup>−</sup> → Be
| −1.97
|-
| 13
| Al
| [[aluminium]]
| Al<sup>3+</sup> + 3 e<sup>−</sup> → Al
| −1.68
|-
| 22
| Ti
| [[titanium]]
| Ti<sup>3+</sup> + 3 e<sup>−</sup> → Ti
| −1.37
|-
| 25
| Mn
| [[manganese]]
| Mn<sup>2+</sup> + 2 e<sup>−</sup> → Mn
| −1.18
|-
| 23
| V
| [[vanadium]]
| V<sup>2+</sup> + 2 e<sup>−</sup> → V
| −1.12
|-
| 24
| Cr
| [[chromium]]
| Cr<sup>2+</sup> + 2 e<sup>−</sup> → Cr
| −0.89
|-
| 30
| Zn
| [[zinc]]
| Zn<sup>2+</sup> + 2 e<sup>−</sup> → Zn
| −0.76
|-
| 31
| Ga
| [[gallium]]
| Ga<sup>3+</sup> + 3 e<sup>−</sup> → Ga
| −0.55
|-
| 26
| Fe
| [[iron]]
| Fe<sup>2+</sup> + 2 e<sup>−</sup> → Fe
| −0.44
|-
| 48
| Cd
| [[cadmium]]
| Cd<sup>2+</sup> + 2 e<sup>−</sup> → Cd
| −0.40
|-
| 49
| In
| [[indium]]
| In<sup>3+</sup> + 3 e<sup>−</sup> → In
| −0.34
|-
| 81
| Tl
| [[thallium]]
| Tl<sup>+</sup> + e<sup>−</sup> → Tl
| −0.34
|-
| 27
| Co
| [[cobalt]]
| Co<sup>2+</sup> + 2 e<sup>−</sup> → Co
| −0.28
|-
| 28
| Ni
| [[nickel]]
| Ni<sup>2+</sup> + 2 e<sup>−</sup> → Ni
| −0.24
|-
| 50
| Sn
| [[tin]]
| Sn<sup>2+</sup> + 2 e<sup>−</sup> → Sn
| −0.14
|-
| 82
| Pb
| [[lead]]
| Pb<sup>2+</sup> + 2 e<sup>−</sup> → Pb
| −0.13
|- bgcolor=#ffcccc
| 1
| H
| [[hydrogen]]
| 2 H<sup>+</sup> + 2 e<sup>−</sup> → H<sub>2</sub>
| 0.00
|- bgcolor=#e8e8e8
| 32
| Ge
| [[germanium]]
| Ge<sup>2+</sup> + 2 e<sup>−</sup> → Ge
| +0.1
|- bgcolor=#e8e8e8
| 51
| Sb
| [[antimony]]
| Sb<sup>3+</sup> + 3 e<sup>−</sup> → Sb
| +0.15
|-
| 83
| Bi
| [[bismuth]]
| Bi<sup>3+</sup> + 3 e<sup>−</sup> → Bi
| +0.31
|-
| 29
| Cu
| [[copper]]
| Cu<sup>2+</sup> + 2 e<sup>−</sup> → Cu
| +0.34
|- bgcolor=#e8e8e8
| 84
| Po
| [[polonium]]
| Po<sup>2+</sup> + 2 e<sup>−</sup> → Po
| +0.6
|- bgcolor=#e8e8e8
| 44
| Ru
| [[ruthenium]]
| Ru<sup>3+</sup> + 3 e<sup>−</sup> → Ru
| +0.60
|-
| 45
| Rh
| [[rhodium]]
| Rh<sup>3+</sup> + 3 e<sup>−</sup> → Rh
| +0.76
|-
| 47
| Ag
| [[silver]]
| Ag<sup>+</sup> + e<sup>−</sup> → Ag
| +0.80
|-
| 80
| Hg
| [[mercury (element)|mercury]]
| Hg<sup>2+</sup> + 2 e<sup>−</sup> → Hg
| +0.85
|-
| 46
| Pd
| [[palladium]]
| Pd<sup>2+</sup> + 2 e<sup>−</sup> → Pd
| +0.92
|- bgcolor=#e8e8e8
| 77
| Ir
| [[iridium]]
| Ir<sup>3+</sup> + 3 e<sup>−</sup> → Ir
| +1.0
|- bgcolor=#e8e8e8
| 85
| At
| [[astatine]]
| At<sup>+</sup> + e<sup>−</sup> → At
| +1.0
|-
| 78
| Pt
| [[platinum]]
| Pt<sup>2+</sup> + 2 e<sup>−</sup> → Pt
| +1.18
|- bgcolor=#e8e8e8
| 79
| Au
| [[gold]]
| Au<sup>3+</sup> + 3 e<sup>−</sup> → Au
| +1.50
|}

The positions of [[lithium]] and [[sodium]] are changed on such a series.

Standard electrode potentials offer a quantitative measure of the power of a reducing agent, rather than the qualitative considerations of other reactive series. However, they are only valid for ''standard'' conditions: in particular, they only apply to reactions in aqueous solution. Even with this proviso, the electrode potentials of lithium and sodium – and hence their positions in the electrochemical series – appear anomalous. The order of reactivity, as shown by the vigour of the reaction with water or the speed at which the metal surface tarnishes in air, appears to be
:Cs > K > Na > Li > alkaline earth metals,
i.e., alkali metals > alkaline earth metals,

the same as the reverse order of the (gas-phase) [[Ionization energy|ionization energies]]. This is borne out by the extraction of metallic lithium by the electrolysis of a [[eutectic]] mixture of [[lithium chloride]] and [[potassium chloride]]: lithium metal is formed at the cathode, not potassium.<ref name="G&E">{{Greenwood&Earnshaw1st|pages=82–87}}</ref>