One chemical property is reactivity. Not all substances are equally reactive. Reactivity relates to how readily something undergoes a chemical reaction.
Reactivity describes how readily a substance undergoes a chemical reaction. Some substances react very easily, while others are much less likely to react under the same conditions.
There's another characteristic of matter related to how likely something is to react.
In an imaginary way, you could think that if you throw some (let's say fluorine) into a bucket and then toss two other things—a metal probably—in, which one will react? Whichever one will react is higher on the activity series. While activity and electronegativity are both related to electron behavior, the activity series does not perfectly follow electronegativity, especially for metals.
When predicting products, we sometimes need to answer a simple question:
If two elements are competing for the same place in a compound, which one wins?
That is where the activity series comes in.
So, given two different elements in a potential replacement reaction, which one is more likely to replace the other? Their relative activity can be organized into a ranked list.
What Is an Activity Series?
An activity series is a ranking of elements according to their relative tendency to participate in certain chemical reactions.
Metals near the top of the activity series lose electrons more readily than metals near the bottom.
The activity series does not perfectly follow electronegativity. Both concepts involve electrons, but they describe different properties. When predicting single-replacement reactions, use the activity series, not electronegativity.
Activity Series: The reactivity series is a list of metals ranked in order of decreasing of relative tendency to react. (More)
Using the Activity Series
In a single-replacement reaction, an element can generally replace another element that is below it in the appropriate activity series.
An element cannot replace an element above it.
If the replacement cannot occur, the result is:
NR = No Reaction
For example, if metal A is above metal B:
A + BC → AC + B
A can replace B.
However, if A is below B:
A + BC → NR
The activity series is a useful prediction tool, but real reactions can also be affected by concentration, temperature, surface coatings, and other reaction conditions.
Metal Activity Series
Most active / most easily oxidized
The following list gives an extended version of a metal activity series. In a typical single-replacement reaction, a free metal can replace a metal ion that is below it in the series. A metal generally cannot replace a metal ion that is above it. If replacement cannot occur, the reaction is written as NR (No Reaction).
The metal activity series below is arranged from most active to least active:
Most active or most easily oxidizedLithium Li(s) → Li⁺(aq) + e⁻
Cesium Cs(s) → Cs⁺(aq) + e⁻
Rubidium Rb(s) → Rb⁺(aq) + e⁻
Potassium K( s ) → K 1+ ( aq ) + e –
Barium Ba( s ) → Ba 2+ ( aq ) + 2e –
Strontium Sr(s) → Sr²⁺(aq) + 2e⁻
Calcium Ca( s ) → Ca 2+ ( aq ) + 2e –
Sodium Na(s) → Na⁺(aq) + e⁻
Magnesium Mg( s ) → Mg 2+ ( aq ) + 2e –
Beryllium Be(s) → Be²⁺(aq) + 2e⁻
Aluminum Al( s ) → Al 3+ ( aq ) + 3e –
Manganese Mn (s) → Mn 2+ ( aq ) + 2e –
Zinc Zn( s ) → Zn 2+ ( aq ) + 2e –
Chromium Cr(s) → Cr³⁺(aq) + 3e⁻
Iron Fe( s ) → Fe 2+ ( aq ) + 2e –
Cadmium Cd(s) → Cd²⁺(aq) + 2e⁻
Cobalt Co( s ) → Co 2+ ( aq ) + 2e –
Nickel Ni( s ) → Ni 2+ ( aq ) + 2e –
Tin Sn( s ) → Sn 2+ ( aq ) + 2e –
Lead Pb( s ) → Pb 2+ ( aq ) + 2e –
Hydrogen H₂(g) → 2H⁺(aq) + 2e⁻
Bismuth Bi(s) → Bi³⁺(aq) + 3e⁻
Copper Cu( s ) → Cu 2+ ( aq ) + 2e –
*Silver Ag( s ) → Ag + ( aq ) + e –
*Mercury Hg( l ) → Hg 2+ ( aq ) + 2e – *Some sources swap Hg and Ag (e.g. this)
Palladium Pd(s) → Pd²⁺(aq) + 2e⁻
Least active or most difficult to oxidizePlatinum Pt( s ) → Pt 2+ ( aq ) + 2e –
Gold Au( s ) → Au 3+ ( aq ) + 3e –
NOTE: Hydrogen is not a metal. It is included as a reference point. Metals above hydrogen can generally replace H⁺ from ordinary dilute acids; metals below hydrogen generally cannot.
Nonmetals
For nonmetals, electronegativity can provide a general guide to an element's tendency to attract electrons, but electronegativity should not be treated as a universal nonmetal activity series.
(Most electronegative to least)
Oxygen O 3.44
Chlorine Cl 3.16
Iodine I 2.66
Hydrogen H 2.20
The Big Rule
For single-replacement reactions:
Higher replaces lower within the appropriate activity series.
If the free element is above the element it is attempting to replace in the appropriate metal or halogen activity series, a reaction can occur.
NR — No Reaction
Use the metal activity series for metal replacement and the halogen activity series for halogen replacement.
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A few sources…
https://www.thoughtco.com/activity-series-of-metals-603960
https://courses.lumenlearning.com/cheminter/chapter/chart-activity-series-of-metals/
https://www.sd308.org/cms/lib/IL01906463/Centricity/Domain/2189/Activity%20Series%20Chart.pdf
http://foradorimath.weebly.com/uploads/4/6/3/5/4635110/2a_-_activity_series.pdf
https://en.wikipedia.org/wiki/Reactivity_series#Table
Comments:
Different sources sometimes show slightly different activity-series rankings. One important example is lithium. Lithium may appear lower in simplified reactivity charts, especially when visible reactions with water are being considered. However, when metals are compared using standard aqueous electrode potentials, lithium has an exceptionally strong tendency to be oxidized.
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