Certain soft and weak elements do not conduct heat or electricity, are neither malleable nor ductile, and are brittle. Such metals are called non-metals. Only 22 of the 118 known elements are non-metals. Non-metals include carbon, oxygen, nitrogen, and sulphur, to name a few. In this article, we will learn about various chemical properties of non-metals and their reaction with different elements and compounds.

Chemical Properties of Non-metals

A large amount of energy is released when a non-metal accepts one or more electrons. On the other hand, a large amount of energy is needed to remove one or more electrons from non-metals. Hence non-metals do not form positively charged ions but readily form negatively charged ions. Thus, the non-metals are electropositive elements. It can be represented in the equation as:

1. \(\mathop {{\rm{Cl}}}\limits_{{\rm{Chlorine}}\,{\rm{atom}}} + {{\rm{e}}^ – } \to \mathop {{\rm{C}}{{\rm{l}}^ – }}\limits_{{\rm{Chloride}}\,{\rm{ion}}} \)
2. \(\mathop {\rm{O}}\limits_{{\rm{Oxygen}}\,{\rm{atom}}} + 2{{\rm{e}}^ – } \to \mathop {{{\rm{O}}^{2 – }}}\limits_{{\rm{Oxide}}\,{\rm{ion}}} \)
3. \(\mathop {\rm{S}}\limits_{{\rm{Sulphur}}\,{\rm{atom}}} + 2{{\rm{e}}^ – } \to \mathop {{{\rm{S}}^{2 – }}}\limits_{{\rm{Sulphide}}\,{\rm{ion}}} \)
4. \(\mathop {\rm{N}}\limits_{{\rm{Nitrogen}}\,{\rm{atom}}} + 3{{\rm{e}}^ – } \to \mathop {{{\rm{N}}^{3 – }}}\limits_{{\rm{Nitride}}\,{\rm{ion}}} \)

Reaction of Non-metals with Oxygen

Non-metals react with oxygen on heating to form oxides. These oxides may be acidic or neutral oxides. But they do not form basic oxides. The acidic oxides of non-metals dissolve in water to form acids.
Let us illustrate the chemical reactions of a few non-metals with oxygen.

Acidic Oxides

The non-metallic oxides which dissolve in water to form acids are called acidic oxides.

Example 1: Reaction of carbon with oxygen

When carbon burns in excess of air, it forms carbon dioxide, which is an acidic oxide. This oxide dissolves in water to form carbonic acid. The chemical equation involved is as follows.

\({\rm{C}} + {{\rm{O}}_2} \to {\rm{C}}{{\rm{O}}_2}\)

\({\rm{C}}{{\rm{O}}_2} + {{\rm{H}}_2}{\rm{O}} \to {{\rm{H}}_2}{\rm{C}}{{\rm{O}}_3}\)

Example 2: Reaction of sulphur with oxygen

When sulphur reacts with oxygen, it forms sulphur dioxide, an acidic oxide. It dissolves in water to form sulphurous acid. The chemical equation involved is as follows:

\({\rm{S}}\left( {\rm{s}} \right) + {{\rm{O}}_2}\left( {\rm{g}} \right) \to {\rm{S}}{{\rm{O}}_2}\left( {\rm{g}} \right)\)

\({\rm{S}}{{\rm{O}}_2}\left( {\rm{g}} \right) + {{\rm{H}}_2}{\rm{O}}\left( {\rm{l}} \right) \to {{\rm{H}}_2}{\rm{S}}{{\rm{O}}_3}\left( {{\rm{aq}}} \right)\)

Neutral Oxides

The non-metallic oxides that neither reacts with acid nor with bases are called neutral oxides. Let us illustrate this reaction with a few non-metals.

Example 1: Reaction of carbon with oxygen

When carbon burns in a limited supply of oxygen, it forms carbon monoxide.

\(2{\rm{C}} + {{\rm{O}}_2} \to 2{\rm{CO}}\)

The carbon monoxide thus formed does not produce acid with water.

Example 2: Reaction of hydrogen with oxygen

When hydrogen combines with oxygen, it forms water. This reaction takes place only when an electric spark is introduced.

\(2{{\rm{H}}_2} + {{\rm{O}}_2} \to 2{{\rm{H}}_2}{\rm{O}}\)

Example 3: Reaction of nitrogen with oxygen

Nitrogen and oxygen react at a high temperature of about 2700°C-3000℃ to produce a low yield of nitric oxide.

\({{\rm{N}}_2}\left( {\rm{g}} \right) + {{\rm{O}}_2}\left( {\rm{g}} \right) \to 2{\rm{NO}}\)

In all of the above reactions, all the non-metallic oxides are formed by sharing electrons, and so are covalent compounds. Hence, non-metallic oxides do not contain any oxide ions.

Reactions of Non-metals with Water

Usually, non-metals do not react with water to produce hydrogen gas. This is because non-metals cannot reduce hydrogen ions of water to hydrogen gas. But a few highly reactive non-metals such as fluorine react with water to form oxygen or ozone \(\left( {{{\rm{O}}_3}} \right)\) molecules. The reactions involved are as follows.

\(2{{\rm{F}}_2}\left( {\rm{g}} \right) + 2{{\rm{H}}_2}{\rm{O}}\left( {\rm{l}} \right) \to 4{\rm{HF}}\left( {{\rm{aq}}} \right) + {{\rm{O}}_2}\left( {\rm{g}} \right)\)

\({\rm{3}}{{\rm{F}}_2}\left( {\rm{g}} \right) + 3{{\rm{H}}_2}{\rm{O}}\left( {\rm{l}} \right) \to 6{\rm{HF}}\left( {{\rm{aq}}} \right) + {{\rm{O}}_3}\left( {\rm{g}} \right)\)

Reaction of Non-metals with Dilute Acids

Non-metals do not react with dilute acids. In other words, non-metals do not displace hydrogen from acids. For example, the non-metals like carbon, sulphur and phosphorus do not react with dilute hydrochloric acid or dilute sulphuric acid to produce hydrogen gas. Let us see why non-metals are not able to displace hydrogen from acids.

In order to displace hydrogen ions \(\left( {{{\rm{H}}^ + }} \right)\) of an acid and convert them into hydrogen gas, electrons should be supplied to the hydrogen ions of the acid. Now, a non-metal, being itself, an acceptor of electrons, cannot give electrons to the hydrogen ions of the acid to reduce them to hydrogen gas.

And hence the non-metals are not able to displace hydrogen ions from acids to form hydrogen gas. Thus, if non-metals like carbon, sulphur, phosphorus are put into a test tube containing dilute sulphuric acid (or dilute hydrochloric acid), then no hydrogen gas is evolved.

Reaction of Non-metals with Salt Solutions

Generally, a more reactive non-metal displaces less reactive non-metal from its salt solution. We can illustrate this with a few examples.

Example 1: Reaction of chlorine with sodium bromide

\({\rm{C}}{{\rm{l}}_2}\left( {\rm{g}} \right) + 2{\rm{NaBr}}\left( {{\rm{aq}}} \right) \to 2{\rm{NaCl}}\left( {{\rm{aq}}} \right) + {\rm{B}}{{\rm{r}}_2}\left( {\rm{g}} \right)\)

When chlorine gas is passed through a solution of sodium bromide, sodium chloride, along with bromine gas, is formed. In this reaction, more reactive non-metal chlorine displaces less reactive non-metal bromine from its salt solution sodium bromide.

Example 2: Reaction of chlorine with potassium iodide

When chlorine gas is passed through a solution of potassium iodide, potassium chloride, along with iodine gas, is formed.

\({\rm{C}}{{\rm{l}}_2}\left( {\rm{g}} \right) + 2{\rm{KI}}\left( {{\rm{aq}}} \right) \to 2{\rm{KCl}}\left( {{\rm{aq}}} \right) + {{\rm{I}}_2}\left( {\rm{S}} \right)\)

In this reaction, more reactive non-metal chlorine displaces less reactive non-metal iodine from its salt solution potassium iodide.

Reaction of Non-metals with Chlorine

Generally, non-metals react with chlorine to form covalent chlorides. This is because these chlorides are formed by sharing of electrons between the atoms of non-metals and the chlorine. Hence, these chlorides are covalent compounds. These chlorides are non-electrolytes as they do not conduct electricity. These chlorides are also volatile liquids or gases.
Let us illustrate the reaction between non-metals and chlorine with a few examples.

Example 1: Reaction of hydrogen and chlorine

When hydrogen reacts with chlorine in the presence of diffused sunlight, it forms hydrogen chloride gas.

\({\rm{C}}{{\rm{l}}_2} + {{\rm{H}}_2} \to 2{\rm{HCl}}\)

Example 2: Reaction of phosphorus and chlorine

When phosphorus reacts with chlorine, it forms phosphorus trichloride.

\(6{\rm{C}}{{\rm{l}}_2} + {{\rm{P}}_4} \to 4{\rm{PC}}{{\rm{l}}_3}\)

Sometimes phosphorus reacts with excess chlorine to form phosphorus pentachloride \(\left( {{\rm{PC}}{{\rm{l}}_5}} \right).\)

Example 3: Reaction of carbon with chlorine

When carbon reacts with chlorine, it forms carbon tetrachloride \(\left( {{\rm{CC}}{{\rm{l}}_4}} \right).\)

\(2{\rm{C}}{{\rm{l}}_2}\left( {\rm{g}} \right) + {\rm{C}}\left( {\rm{s}} \right) \to {\rm{CC}}{{\rm{l}}_4}\left( {\rm{l}} \right)\)

Reaction with Hydrogen

Non-metals react with hydrogen to form covalent hydrides. The sharing of electrons forms the non-metal hydrides. That is, non-metal hydrides are formed by covalent bonding. Here are some examples.

1. Sulphur is a non-metal which combines with hydrogen to form a covalent hydride called hydrogen sulphide, \({{\rm{H}}_2}{\rm{S}}{\rm{.}}\)
2. \(\mathop {{\rm{S}}\left( {\rm{s}} \right)}\limits_{{\rm{Sulphur}}} + \mathop {{{\rm{H}}_2}\left( {\rm{g}} \right)}\limits_{{\rm{Hydrogen}}} \to \mathop {{{\rm{H}}_2}{\rm{S}}\left( {\rm{g}} \right)}\limits_{{\rm{Hydrogen}}\,{\rm{sulphide}}} \)
3. The hydrogen sulphide gas has the characteristic smell resembling the smell of rotten eggs.
4. Nitrogen is a non-metal that combines with hydrogen in the presence of an iron catalyst to form a covalent hydride called ammonia.
5. \(\mathop {{{\rm{N}}_2}\left( {\rm{g}} \right)}\limits_{{\rm{Nitrogen}}} + \mathop {{\rm{3}}{{\rm{H}}_2}\left( {\rm{g}} \right)}\limits_{{\rm{Hydrogen}}} \to \mathop {{\rm{2N}}{{\rm{H}}_3}\left( {\rm{g}} \right)}\limits_{{\rm{Ammonia}}} \)

Oxygen is also a non-metal which combines with hydrogen to form a hydride called water. Similarly, the hydride of carbon in methane and the hydride of chlorine is \({\rm{HCl}}.\) The non-metal hydrides are covalent compounds formed by the sharing of electrons. Non-metals form covalent hydrides because non-metal atoms cannot give electrons to hydrogen atoms to form hydride ions. Non-metal hydrides are liquids or gases. Non-metal hydrides do not contain ions, and hence they do not conduct electricity. Non-metal hydrides are stable compounds.

Differences Between Metals and Non-metals

Metal	Non-metal
Metals form positive ions. Examples: \({\rm{N}}{{\rm{a}}^ + },\,{{\rm{K}}^ + },\,{\rm{C}}{{\rm{a}}^{2 + }},\,{\rm{M}}{{\rm{g}}^{2 + }},\,{\rm{F}}{{\rm{e}}^{2 + }},\) etc..	Non-metals form negative ions. Examples: \({\rm{C}}{{\rm{l}}^ – },\,{{\rm{S}}^{2 – }},\,{{\rm{N}}^{3 – }},\) etc..
Oxides of metals are basic in nature, i.e., the oxides of metals react with water to give bases or alkalis. \({\rm{N}}{{\rm{a}}_2}{\rm{O}} + {{\rm{H}}_2}{\rm{O}} \to 2{\rm{NaOH}}\) \({\rm{CaO}} + {{\rm{H}}_2}{\rm{O}} \to {\rm{Ca}}{\left( {{\rm{OH}}} \right)_2}\)	Oxides of non-metals are acidic in nature, i.e., the oxides of non-metals react with water to give acids. \({\rm{C}}{{\rm{O}}_2} + {{\rm{H}}_2}{\rm{O}} \to {{\rm{H}}_2}{\rm{C}}{{\rm{O}}_3}\) \({\rm{S}}{{\rm{O}}_2} + {{\rm{H}}_2}{\rm{O}} \to {{\rm{H}}_2}{\rm{S}}{{\rm{O}}_3}\) \({\rm{S}}{{\rm{O}}_3} + {{\rm{H}}_2}{\rm{O}} \to {{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4}\)
Metals dissolve in dilute acids to produce hydrogen gas. \({\rm{Zn}} + {{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4} \to {\rm{ZnS}}{{\rm{O}}_4} + {{\rm{H}}_2}\) Exceptions Some metals do not produce hydrogen when treated with an acid under ordinary circumstances.	Non-metals generally do not dissolve in dilute acids.
Metals, in general do not combine with hydrogen. Exceptions Some metals (\({\rm{Na}},\,{\rm{Ca}},\,{\rm{Li}},\,{\rm{Be}}\) etc.) combine with hydrogen to form non-volatile unstable hydrides.	Non-metals combine with hydrogen to form stable compounds.
Metallic chlorides are generally not hydrolyzed by water or are only partially hydrolyzed. \({\rm{NaCl}} + {{\rm{H}}_2}{\rm{O}} \to {\rm{No}}\,{\rm{hydrolysis}}\) \({\rm{AlC}}{{\rm{l}}_3} + 3{{\rm{H}}_2}{\rm{O}} \to {\rm{Al}}{\left( {{\rm{OH}}} \right)_3} + 3{\rm{HCl}}\)	Chlorides of non-metals are usually hydrolyzed by water. \({\rm{PC}}{{\rm{I}}_3} + 3{{\rm{H}}_2}{\rm{O}} \to 3{\rm{HCl}} + {{\rm{H}}_3}{\rm{P}}{{\rm{O}}_3}\) \({\rm{SiC}}{{\rm{l}}_4} + 4{{\rm{H}}_2}{\rm{O}} \to {\rm{Si}}{\left( {{\rm{OH}}} \right)_4} + 4{\rm{HCl}}\)

Learn Uses of Metals and Non-Metals

Summary

There are only \(22\) non-metallic elements, of which \(11\) are gases, one is a liquid, and the rest \(10\) are solids. Oxygen is a non-metal which is essential for our survival. Non- metal form anions by gaining electrons to complete their octet. In this article, we learn about how the non-metals react with water, oxygen, dilute acids, salt solutions, chlorine and hydrogen.

FAQs

Q.1. What are the chemical properties of non-metal?
Ans:
(a) At room temperature, most non-metals do not react with air.
(b) The only non-metal is white phosphorus, which burns to generate its oxide after reacting with air.
(c) Non-metals exist in all states of matter at room temperature.
(d) Alloys do not form with non-metals. Some elements, such as carbon, silicon, and phosphorus, can form.
(e) Non-metals do not react with dilute acids.

Q.2. What are 4 chemical properties?
Ans: The four chemical properties are:
(a) Non-metals are electronegative elements.
(b) Non-metals form acidic or neutral oxides.
(c) Non-metals form covalent chlorides.
(d) Non-metals behave as oxidizing agents.

Q.3. What are the chemical differences between metals and non-metals?
Ans: The chemical differences between metals and non-metals are:

Reaction with	Metals	Non-metals
Oxygen	Metal oxides are formed, which are generally basic in nature.	Non-metal oxides are formed, which are generally acidic in nature.
Water	Metal hydroxides are formed.	Generally, do not react.
Dilute acid	Metals more reactive than hydrogen displace hydrogen from dilute acids to form metal salts and hydrogen gas.	Do not react with dilute acids.
Salt solution	More reactive metal displaces less reactive metal from its salt solution.	Non-metal that is more reactive displaces less reactive non-metal from its salt solution.
Chlorine	Metal chlorides are formed, which are ionic in nature.	Non-metal chlorides are formed, which are covalent in nature.
Hydrogen	Ionic metal hydrides are formed by reactive metals.	Covalent hydrides are formed.

Q.4. What happens when the non-metal oxide is dissolved in water?
Ans: Some oxides of non-metals are acidic in nature and form acids when dissolved in water. For example, when sulphur dioxide is dissolved in water, the product obtained is sulphurous acid. This reaction is as follows:
\({\rm{S}}{{\rm{O}}_2} + {{\rm{H}}_2}{\rm{O}} \to {{\rm{H}}_2}{\rm{S}}{{\rm{O}}_3}\)

Q.5. Why are non-metals called electronegative elements?
Ans: Non-metals are called electronegative elements as they have the tendency to accept electrons to obtain a stable electronic configuration. Thus, by accepting electrons, non-metals form negatively charged ions. Hence, non-metals are called electronegative elements.

Q.6. What is the nature of oxides of non-metals? How will you justify their nature?
Ans: The oxides formed by most of the non-metals are acidic in nature. For example, \({\rm{C}}{{\rm{O}}_2}\) and \({\rm{S}}{{\rm{O}}_2}\) are acidic in nature. Their reaction shows the acidic nature of these oxides to water.
Carbon dioxide dissolves in water to form carbonic acid. Thus, it is acidic in nature.
\(\mathop {{\rm{C}}{{\rm{O}}_2}\left( {\rm{g}} \right)}\limits_{{\rm{Carbon}}\,{\rm{dioxide}}} + \mathop {{{\rm{H}}_2}{\rm{O}}\left( {\rm{l}} \right)}\limits_{{\rm{Water}}} \to \mathop {{{\rm{H}}_2}{\rm{C}}{{\rm{O}}_3}\left( {{\rm{aq}}} \right)}\limits_{{\rm{Carbon}}\,{\rm{acid}}} \)
Sulphur dioxide also dissolves in water to form an acid called sulphurous acid. Thus, it is also acidic in nature.
\(\mathop {{\rm{S}}{{\rm{O}}_2}\left( {\rm{g}} \right)}\limits_{{\rm{Sulphur}}\,{\rm{dioxide}}} + \mathop {{{\rm{H}}_2}{\rm{O}}\left( {\rm{l}} \right)}\limits_{{\rm{Water}}} \to \mathop {{{\rm{H}}_2}{\rm{S}}{{\rm{O}}_3}\left( {{\rm{aq}}} \right)}\limits_{{\rm{Sulphurous}}\,{\rm{acid}}} \)