In chemistry, a reactivity series (or reactivity series of elements) is an empirical, calculated, and structurally analytical progression [1] of a series of metals, arranged by their "reactivity" from highest to lowest. [2] [3] [4] It is used to summarize information about the reactions of metals with acids and water, single displacement reactions and the extraction of metals from their ores. [5]
Metal | Ion | Reactivity | Extraction |
---|---|---|---|
Caesium Cs | Cs+ | reacts with cold water | Electrolysis (a.k.a. electrolytic refining) |
Rubidium Rb | Rb+ | ||
Potassium K | K+ | ||
Sodium Na | Na+ | ||
Lithium Li | Li+ | ||
Barium Ba | Ba2+ | ||
Strontium Sr | Sr2+ | ||
Calcium Ca | Ca2+ | ||
Magnesium Mg | Mg2+ | reacts very slowly with cold water, but rapidly in boiling water, and very vigorously with acids | |
Beryllium Be | Be2+ | reacts with acids and steam | |
Aluminium Al | Al3+ | ||
Titanium Ti | Ti4+ | reacts with concentrated mineral acids | pyrometallurgical extraction using magnesium, or less commonly other alkali metals, hydrogen or calcium in the Kroll process |
Manganese Mn | Mn2+ | reacts with acids; very poor reaction with steam | smelting with coke |
Zinc Zn | Zn2+ | ||
Chromium Cr | Cr3+ | aluminothermic reaction | |
Iron Fe | Fe2+ | smelting with coke | |
Cadmium Cd | Cd2+ | ||
Cobalt Co | Co2+ | ||
Nickel Ni | Ni2+ | ||
Tin Sn | Sn2+ | ||
Lead Pb | Pb2+ | ||
Antimony Sb | Sb3+ | may react with some strong oxidizing acids | heat or physical extraction |
Bismuth Bi | Bi3+ | ||
Copper Cu | Cu2+ | reacts slowly with air | |
Tungsten W | W3+[ citation needed ] | may react with some strong oxidizing acids | |
Mercury Hg | Hg2+ | ||
Silver Ag | Ag+ | ||
Gold Au | Au3+ [6] [7] | ||
Platinum Pt | Pt4+ |
Going from the bottom to the top of the table the metals:
There is no unique and fully consistent way to define the reactivity series, but it is common to use the three types of reaction listed below, many of which can be performed in a high-school laboratory (at least as demonstrations). [6]
The most reactive metals, such as sodium, will react with cold water to produce hydrogen and the metal hydroxide:
Metals in the middle of the reactivity series, such as iron, will react with acids such as sulfuric acid (but not water at normal temperatures) to give hydrogen and a metal salt, such as iron(II) sulfate:
There is some ambiguity at the borderlines between the groups. Magnesium, aluminium and zinc can react with water, but the reaction is usually very slow unless the metal samples are specially prepared to remove the surface passivation layer of oxide which protects the rest of the metal. Copper and silver will react with nitric acid; but because nitric acid is an oxidizing acid, the oxidizing agent is not the H+ ion as in normal acids, but the NO3− ion.
The reactivity series is sometimes quoted in the strict reverse order of standard electrode potentials, when it is also known as the "electrochemical series". [8]
The following list includes the metallic elements of the first six periods. It is mostly based on tables provided by NIST. [9] [10] 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.) [11]
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.
Z | Sym | Element | Reaction | E° (V) |
---|---|---|---|---|
3 | Li | lithium | Li+ + e− → Li | −3.04 |
55 | Cs | caesium | Cs+ + e− → Cs | −3.03 |
37 | Rb | rubidium | Rb+ + e− → Rb | −2.94 |
19 | K | potassium | K+ + e− → K | −2.94 |
56 | Ba | barium | Ba2+ + 2 e− → Ba | −2.91 |
38 | Sr | strontium | Sr2+ + 2 e− → Sr | −2.90 |
20 | Ca | calcium | Ca2+ + 2 e− → Ca | −2.87 |
11 | Na | sodium | Na+ + e− → Na | −2.71 |
57 | La | lanthanum | La3+ + 3 e− → La | −2.38 |
39 | Y | yttrium | Y3+ + 3 e− → Y | −2.38 |
12 | Mg | magnesium | Mg2+ + 2 e− → Mg | −2.36 |
59 | Pr | praseodymium | Pr3+ + 3 e− → Pr | −2.35 |
58 | Ce | cerium | Ce3+ + 3 e− → Ce | −2.34 |
68 | Er | erbium | Er3+ + 3 e− → Er | −2.33 |
67 | Ho | holmium | Ho3+ + 3 e− → Ho | −2.33 |
60 | Nd | neodymium | Nd3+ + 3 e− → Nd | −2.32 |
69 | Tm | thulium | Tm3+ + 3 e− → Tm | −2.32 |
62 | Sm | samarium | Sm3+ + 3 e− → Sm | −2.30 |
61 | Pm | promethium | Pm3+ + 3 e− → Pm | −2.30 |
66 | Dy | dysprosium | Dy3+ + 3 e− → Dy | −2.29 |
71 | Lu | lutetium | Lu3+ + 3 e− → Lu | −2.28 |
65 | Tb | terbium | Tb3+ + 3 e− → Tb | −2.28 |
64 | Gd | gadolinium | Gd3+ + 3 e− → Gd | −2.28 |
70 | Yb | ytterbium | Yb3+ + 3 e− → Yb | −2.19 |
21 | Sc | scandium | Sc3+ + 3 e− → Sc | −2.09 |
63 | Eu | europium | Eu3+ + 3 e− → Eu | −1.99 |
4 | Be | beryllium | Be2+ + 2 e− → Be | −1.97 |
13 | Al | aluminium | Al3+ + 3 e− → Al | −1.68 |
22 | Ti | titanium | Ti3+ + 3 e− → Ti | −1.37 |
25 | Mn | manganese | Mn2+ + 2 e− → Mn | −1.18 |
23 | V | vanadium | V2+ + 2 e− → V | −1.12 |
24 | Cr | chromium | Cr2+ + 2 e− → Cr | −0.89 |
30 | Zn | zinc | Zn2+ + 2 e− → Zn | −0.76 |
31 | Ga | gallium | Ga3+ + 3 e− → Ga | −0.55 |
26 | Fe | iron | Fe2+ + 2 e− → Fe | −0.44 |
48 | Cd | cadmium | Cd2+ + 2 e− → Cd | −0.40 |
49 | In | indium | In3+ + 3 e− → In | −0.34 |
81 | Tl | thallium | Tl+ + e− → Tl | −0.34 |
27 | Co | cobalt | Co2+ + 2 e− → Co | −0.28 |
28 | Ni | nickel | Ni2+ + 2 e− → Ni | −0.24 |
50 | Sn | tin | Sn2+ + 2 e− → Sn | −0.14 |
82 | Pb | lead | Pb2+ + 2 e− → Pb | −0.13 |
1 | H | hydrogen | 2 H+ + 2 e− → H2 | 0.00 |
32 | Ge | germanium | Ge2+ + 2 e− → Ge | +0.1 |
51 | Sb | antimony | Sb3+ + 3 e− → Sb | +0.15 |
83 | Bi | bismuth | Bi3+ + 3 e− → Bi | +0.31 |
29 | Cu | copper | Cu2+ + 2 e− → Cu | +0.34 |
84 | Po | polonium | Po2+ + 2 e− → Po | +0.6 |
44 | Ru | ruthenium | Ru3+ + 3 e− → Ru | +0.60 |
45 | Rh | rhodium | Rh3+ + 3 e− → Rh | +0.76 |
47 | Ag | silver | Ag+ + e− → Ag | +0.80 |
80 | Hg | mercury | Hg2+ + 2 e− → Hg | +0.85 |
46 | Pd | palladium | Pd2+ + 2 e− → Pd | +0.92 |
77 | Ir | iridium | Ir3+ + 3 e− → Ir | +1.0 |
85 | At | astatine | At+ + e− → At | +1.0 |
78 | Pt | platinum | Pt2+ + 2 e− → Pt | +1.18 |
79 | Au | gold | Au3+ + 3 e− → 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
i.e., alkali metals > alkaline earth metals,
the same as the reverse order of the (gas-phase) 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. [1]
The image shows a periodic table extract with the electronegativity values of metals. [12]
Wulfsberg [13] distinguishes:
very electropositive metals with electronegativity values below 1.4
electropositive metals with values between 1.4 and 1.9; and
electronegative metals with values between 1.9 and 2.54.
From the image, the group 1–2 metals and the lanthanides and actinides are very electropositive to electropositive; the transition metals in groups 3 to 12 are very electropositive to electronegative; and the post-transition metals are electropositive to electronegative. The noble metals, inside the dashed border (as a subset of the transition metals) are very electronegative.
The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). Together with hydrogen they constitute group 1, which lies in the s-block of the periodic table. All alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties. Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour. This family of elements is also known as the lithium family after its leading element.
Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference and identifiable chemical change. These reactions involve electrons moving via an electronically conducting phase between electrodes separated by an ionically conducting and electronically insulating electrolyte.
The halogens are a group in the periodic table consisting of six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though some authors would exclude tennessine as its chemistry is unknown and is theoretically expected to be more like that of gallium. In the modern IUPAC nomenclature, this group is known as group 17.
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity."
Redox is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. The oxidation and reduction processes occur simultaneously in the chemical reaction.
In chemistry, a hydride is formally the anion of hydrogen (H−), a hydrogen atom with two electrons. In modern usage, this is typically only used for ionic bonds, but it is sometimes (and more frequently in the past) been applied to all compounds containing covalently bound H atoms. In this broad and potentially archaic sense, water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. In covalent compounds, it implies hydrogen is attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed.
A noble metal is ordinarily regarded as a metallic element that is generally resistant to corrosion and is usually found in nature in its raw form. Gold, platinum, and the other platinum group metals are most often so classified. Silver, copper, and mercury are sometimes included as noble metals, but each of these usually occurs in nature combined with sulfur.
In chemistry, a reducing agent is a chemical species that "donates" an electron to an electron recipient.
Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula Li[AlH4] or LiAlH4. It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids, and amides. The solid is dangerously reactive toward water, releasing gaseous hydrogen (H2). Some related derivatives have been discussed for hydrogen storage.
Caesium fluoride is an inorganic compound with the formula CsF. A hygroscopic white salt, caesium fluoride is used in the synthesis of organic compounds as a source of the fluoride anion. The compound is noteworthy from the pedagogical perspective as caesium also has the highest electropositivity of all commonly available elements and fluorine has the highest electronegativity.
Thionyl chloride is an inorganic compound with the chemical formula SOCl2. It is a moderately volatile, colourless liquid with an unpleasant acrid odour. Thionyl chloride is primarily used as a chlorinating reagent, with approximately 45,000 tonnes per year being produced during the early 1990s, but is occasionally also used as a solvent. It is toxic, reacts with water, and is also listed under the Chemical Weapons Convention as it may be used for the production of chemical weapons.
In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, RCOO−. It is an anion, an ion with negative charge.
Redox potential is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respectively. Redox potential is expressed in volts (V). Each species has its own intrinsic redox potential; for example, the more positive the reduction potential, the greater the species' affinity for electrons and tendency to be reduced.
Hydrogen telluride is the inorganic compound with the formula H2Te. A hydrogen chalcogenide and the simplest hydride of tellurium, it is a colorless gas. Although unstable in ambient air, the gas can exist long enough to be readily detected by the odour of rotting garlic at extremely low concentrations; or by the revolting odour of rotting leeks at somewhat higher concentrations. Most compounds with Te–H bonds (tellurols) are unstable with respect to loss of H2. H2Te is chemically and structurally similar to hydrogen selenide, both are acidic. The H–Te–H angle is about 90°. Volatile tellurium compounds often have unpleasant odours, reminiscent of decayed leeks or garlic.
Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. As a result, sodium usually forms ionic compounds involving the Na+ cation. Sodium is a reactive alkali metal and is much more stable in ionic compounds. It can also form intermetallic compounds and organosodium compounds. Sodium compounds are often soluble in water.
In chemistry, a Zintl phase is a product of a reaction between a group 1 or group 2 and main group metal or metalloid. It is characterized by intermediate metallic/ionic bonding. Zintl phases are a subgroup of brittle, high-melting intermetallic compounds that are diamagnetic or exhibit temperature-independent paramagnetism and are poor conductors or semiconductors.
The oxidation state of oxygen is −2 in almost all known compounds of oxygen. The oxidation state −1 is found in a few compounds such as peroxides. Compounds containing oxygen in other oxidation states are very uncommon: −1⁄2 (superoxides), −1⁄3 (ozonides), 0, +1⁄2 (dioxygenyl), +1, and +2.
Sodium selenide is an inorganic compound of sodium and selenium with the chemical formula Na2Se.
Nonmetals show more variability in their properties than do metals. Metalloids are included here since they behave predominately as chemically weak nonmetals.
Germyl, trihydridogermanate(1-), trihydrogermanide, trihydridogermyl or according to IUPAC Red Book: germanide is an anion containing germanium bounded with three hydrogens, with formula GeH−3. Germyl is the IUPAC term for the –GeH3 group. For less electropositive elements the bond can be considered covalent rather than ionic as "germanide" indicates. Germanide is the base for germane when it loses a proton.
Li > Cs > Rb > K > Ba > Sr > Ca > Na > La > Y > Mg > Ce > Sc > Be > Al > Ti > Mn > V > Cr > Zn > Ga > Fe > Cd > In > Tl > Co > Ni > Sn > Pb > (H) > Sb > Bi > Cu > Po > Ru > Rh > Ag > Hg > Pd > Ir > Pt > Au