What is activity series Class 8?

What is meant by the metal reactivity series ? State its importance, (any two points).

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Utility of Reactivity Series
Salient Features
Reaction Between Metals and Water
Reaction Between Metals and Acids
Important Uses of Reactivity Series
Frequently Asked Question (FAQs)
Table of Contents
Reaction Between Metals and Water
Reaction Between Metals and Acids
Single Displacement Reactions Between Metals

A list in which the metals are arranged in the decreasing order of their chemical reactivity is called the metal reactivity series.

Special features of the activity series:

The ease with which a metal in solution loses electron(s) and forms a positive ion decreases down the series, i.e. from potassium to gold.
Hydrogen is included in the activity series because, like metals do, it too loses an electron and becomes positively charged (H+) in most chemical reactions.
The series facilitates the comparative study of metals in terms of the degree of their reactivity.
The compounds of the metals (oxides, carbonates, nitrates and hydroxides) too can be easily compared.

Concept: Reactivity Series of Metals

Is there an error in this question or solution?

Solution:

Reactivity series is a series of an arrangement of metals in decreasing order of their reactivity

For example, zinc is above copper in the reactivity series, it implies that zinc is more reactive than copper.

(a) The reaction of metals with water:

Potassium, Sodium and Calcium react with cold water.

Potassium reacts violently and darts on the surface of water.

Sodium bums and revolves on the surface of water.

Calcium reacts less violently and sinks in water.

This implies that Potassium is most reactive and Calcium is least reactive out of the three metals.

Magnesium and Aluminium react with boiling water

They are less reactive than K, Na and Ca.

Zn, Fe, Pb also react with steam and the reaction doesn’t go on for longer,

Metals like Cu, Hg, Ag, Pt do not react with steam or water, hence they are least reactive.

(b) The reaction of metals with acids:

K and Na react with HCl and H2SO4 explosively and Hydrogen gas is produced

$2Na+2HCl\to2NaCl+H_2$

Ca, Mg, Al, Zn and Fe react less strongly with decreasing reactivity.

$Ca+H_2SO_4\toCaSO_4+H_2$

Metals below Hydrogen do not react with acids.

A reactivity series is a series of metals based on their reactivity from highest to lowest. Thus, a metal reactivity series can be defined as a series of metals in order of reactivity from highest to lowest. It is also known as a series of activities. The reactivity of metals is due to their incomplete outer orbitals or their electron configuration. Metals form positively charged ions because they tend to lose electrons. Metals with high atomic numbers are more reactive because their electrons are far from the positively charged nucleus; thus, they can be easily removed.

Reactivity Series of Metal chart are given below:

Utility of Reactivity Series

The reactivity series is very useful as it gives the following information:

The metal which is higher in the activity series is more reactive than the other. Lithium is the most reactive and platinum is the least reactive metal.
The metals which have been placed above hydrogen are more reactive than hydrogen and can displace hydrogen from its compounds like water and acids to liberate hydrogen gas.
The metals which are placed below hydrogen are less reactive than hydrogen and cannot displace hydrogen from its compounds like water and acids.
A more reactive metal (placed higher in the reactivity series) can displace the less reactive metal from the solution of its salt.
Metals at the top of the series are very reactive and, therefore, they do not occur free in nature, while the metals at the bottom of the series are least reactive and, therefore, they normally occur free in nature.

Salient Features

Metals at the top of the series of reactivity are strong reducing agents because they oxidize quickly. These metals tarnish/corrode very easily.
The reducing power of metals weakens as you go through the series.
Electropositivity of elements also decreases as one moves down the metal reactivity series.
All metals above hydrogen in the activity range release hydrogen gas when reacted with dilute HCl or dilute H2SO4.
Metals placed high in the reactivity series can displace metals lower in their salt solutions.
Higher category metals require more energy to isolate from ores and other compounds.

Reaction Between Metals and Water

Calcium and metals that are more reactive than calcium in the reactivity series can react with cold water to form the corresponding hydroxide, releasing hydrogen gas. For example, the reaction between potassium and water yields potassium hydroxide and hydrogen gas as described by the chemical equation below.

2K + 2H2O → 2KOH + H2

Reaction Between Metals and Acids

Lead and the metals are on high lead on the activity series form salts when reacted with sulphuric acid or hydrochloric acid. These reactions also contain the liberation of hydrogen gas. The reaction between sulphuric acid and zinc is an example of such a reaction. Here, zinc sulfate and H2 gas are formed as products. The chemical equation is:

Zn + H2SO4 → ZnSO4 + H2

Important Uses of Reactivity Series

In displacement reaction - Displacement reactions are that reactions in which more reactive metal displaces less reactive metal from its salt. So, by reactivity series, you can also tell that which metal will displace another metal.
The reaction between metals and water - Metals from potassium to calcium will react with cold water to release hydrogen gas.

Chemical Equations for the reaction of K and Ca with cold water are:

K (s) + H2O (l) → KOH (aq) + ½ H2 (g) [Potassium Cold Water Potassium Hydroxide Hydrogen]

Note: Potassium reacts extremely violently with water to form a colorless aqueous solution of KOH with a release of12 mole of H2 gas. The resultant solution is basic because of the dissolved hydroxide.

The reaction between metals and acids - Lead and other different metals that are more reactive than lead in the reactivity series can react with hydrochloric acid and sulphuric acid to form salts. Thus, we are able to predict the reactions by reactivity series. Chemical Equations for the reaction of Pb with HCl and HSO4 to form salts are:

Pb (s) + 2HCl (aq) → PbCl2 (aq) + H2 (g) [Lead Hydrochloric Acid Lead Chloride Hydrogen]

Note: Pb reacts slowly with acids like HCl and HNO3 and releases bubbles of Hydrogen gas on reaction.

Single displacement reaction between metals The high-ranking metals on the reactivity series usually reduce the ions of the low-ranking metals. Thus the high-ranking metal simply displaces the low-ranking metal in a single displacement reaction which occurs b/w them. One of the common displacement reactions is the displacement of copper from copper sulfate by zinc the chemical equation for this reaction is given by:

Zn (s) + CuSO4 (aq) → ZnSO4 (aq) + Cu (s)

This concept is also used in various applications, mostly for the extraction of metals. For example, with the help of the single displacement reaction with magnesium titanium can be extracted from titanium tetrachloride. Thus to predict the result of the single displacement reaction, the reactivity series becomes very helpful.

Frequently Asked Question (FAQs)

Q1. What does reactivity series depend on?

Ans. The reactivity series of metals totally depends on the reactivity of metals which is dependent on the atomic radius, nuclear charge, sublevel electrons arrangement, and shielding effect.

Q2. What is meant by reactivity series of metals?

Ans. A reactivity series of metals is a table listing metals to decrease reactivity. Usually, the more reactive a metal is:, the more vigorously it reacts with different substances. It quickly loses electrons to form positive ions (cations).

Q3. How is reactivity series formed?

Ans. In a reactivity series, the most reactive element is placed at the top and the least reactive element at the bottom. The more reactive metals tend to lose electrons and form positive ions.

Q4. Which metal is most reactive?

Ans. According to the reactivity series, sodium is the most reactive metal.

Q5. Which is the least reactive metal?

Ans. The least reactive metal is Platinum. It has corrosion resistance, even at high temperatures, and is considered a noble metal. Therefore, Platinum is often found chemically uncombined as native Platinum.

The reactivity series of metals, also known as the activity series, refers to the arrangement of metals in the descending order of their reactivities.

The data provided by the reactivity series can be used to predict whether a metal can displace another in a single displacement reaction. It can also be used to obtain information on the reactivity of metals towards water and acids.

A chart of the reactivity series of common metals is provided below.

Metals tend to readily lose electrons and form cations. Most of them react with atmospheric oxygen to form metal oxides. However, different metals have different reactivities towards oxygen (unreactive metals such as gold and platinum do not readily form oxides when exposed to air).

The metals at the top of the reactivity series are powerful reducing agents since they are easily oxidized. These metals tarnish/corrode very easily.
The reducing ability of the metals grows weaker while traversing down the series.
The electro positivity of the elements also reduces while moving down the reactivity series of metals.
All metals that are found above hydrogen in the activity series liberate H2 gas upon reacting with dilute HCl or dilute H2SO4.
Metals that are placed higher on the reactivity series have the ability to displace metals that are placed lower from their salt solutions.
Higher ranking metals require greater amounts of energy for their isolation from ores and other compounds.

Another important feature of the activity series is that while travelling down the series, the electron-donating ability of the metals reduces.

The reactivities of metals are tabulated below (in the descending order) along with their corresponding ions. Note that the metals in Red react with cold water, those in Orange cannot react with cold water but can react with acids, and those in Blue only react with some strong oxidizing acids.

Reactivity Series of Metals	Ions Formed
Caesium	Cs+
Francium	Fr+
Rubidium	Rb+
Potassium	K+
Sodium	Na+
Lithium	Li+
Barium	Ba2+
Radium	Ra2+
Strontium	Sr2+
Calcium	Ca2+
Magnesium	Mg2+
Beryllium	Be2+
Aluminium	Al3+
Titanium	Ti4+
Manganese	Mn2+
Zinc	Zn2+
Chromium	Cr3+
Iron	Fe3+
Cadmium	Cd2+
Cobalt	Co2+
Nickel	Ni2+
Tin	Sn2+
Lead	Pb2+
Hydrogen	H+ (Non-Metal, Reference for Comparison)
Antimony	Sb3+
Bismuth	Bi3+
Copper	Cu2+
Tungsten	W3+
Mercury	Hg2+
Silver	Ag+
Platinum	Pt4+
Gold	Au3+

Despite being a non-metal, hydrogen is often included in the reactivity series since it helps compare the reactivities of the metals. The metals placed above hydrogen in the series can displace it from acids such as HCl and H2SO4 (since they are more reactive).

Apart from providing insight into the properties and reactivities of the metals, the reactivity series has several other important applications. For example, the outcome of the reactions between metals and water, metals and acids, and single displacement reactions between metals can be predicted with the help of the activity series.

Reaction Between Metals and Water

Calcium and the metals that are more reactive than calcium in the reactivity series can react with cold water to form the corresponding hydroxide while liberating hydrogen gas. For example, the reaction between potassium and water yields potassium hydroxide and H2 gas, as described by the chemical equation provided below.

2K + 2H2O → 2KOH + H2

Therefore, the reactivity series of metals can be used to predict the reactions between metals and water.

Reaction Between Metals and Acids

Lead and the metals ranking above lead on the activity series form salts when reacted with hydrochloric acid or sulphuric acid. These reactions also involve the liberation of hydrogen gas. The reaction between zinc and sulphuric acid is an example of such a reaction. Here, zinc sulfate and H2 gas are formed as products. The chemical equation is:

Zn + H2SO4 → ZnSO4 + H2

Thus, the reactions between metals and some acids can be predicted with the help of the reactivity series.

Single Displacement Reactions Between Metals

The ions of low ranking metals are readily reduced by high ranking metals on the reactivity series. Therefore, low ranking metals are easily displaced by high ranking metals in the single displacement reactions between them.

A great example of such a reaction is the displacement of copper from copper sulphate by zinc. The chemical equation for this reaction is given by:

Zn (s) + CuSO4 (aq) → ZnSO4 (aq) + Cu (s)

This concept has several practical applications in the extraction of metals. For example, titanium is extracted from titanium tetrachloride via a single displacement reaction with magnesium. Thus, the reactivity series of metals can also be used to predict the outcome of single displacement reactions.

The metal reactivity series is a list of metals arranged in the order of their decreasing activities. The metals at the top of the series (K, Na, Ca, Mg and Al) are so reactive that they are never found in nature as free elements. It is difficult to separate them from their compounds and extract. The metals at the bottom of the activity series are the least reactive. Some of these metals are found in the earth’s crust in their free state. For example, Gold, Platinum is found in free state. So, it becomes comparatively easier to extract such least reactive metals

Platinum is the least reactive metal. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Consequently, platinum is often found chemically uncombined as native platinum.

Reactivity series is a list of metals arranged in decreasing order of their reactivity. Most reactive metals are at the top while the least reactive metals at the bottom. For any two metals in the series, the metal placed higher in the series can displace lower metals from their salt solution.

alkali metal are most reactive metals. Down the reactivity increases. Francium is most reactive element in periodic table. However, francium is artificial or only few quantities have produced right now, so after the francium, cesium is most reactive metal.

Non-metal properties have a relatively low boiling point, and other non-metals are gases. Likewise, non-metals are poor heat conductors, and solid non-metals are dull and brittle. Many non-metals are strongly reactive, while others are in no way reactive. It depends on the number of electrons in the outer amount of energy.

The reactivity series of metals refers to the array of metals in the descending order of their reactivities. It is also known as the activity series of metals.

The reactivity series of metals depends on the reactivity of metals which is dependent on the atomic radius, nuclear charge, sublevel electrons arrangement and shielding effect.

The reactivity of metal originated from the reactivity of metals. In the activity series of metals more reactive metal is placed on the top of the series while a less reactive metal is placed at the bottom of the series.

The reactivity series of metals is the array of metals in the descending order of their reactivities. It helps in predicting if a metal can displace another metal in a displacement reaction.

Hydrogen is a part of the reactivity series of metals because like metals it also loses electrons to form a positive ion.

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