Introduction: Metals & Non-Metals

Chemical Properties of Metals

• Metals react with air or oxygen to form metal oxide. For Example, Copper reacts with oxygen to form copper oxide.
  Metal + O2 → Metal oxide 2Cu + O2 → 2CuO
  4Al + 3O2 → 2Al2O3

• Oxides of metals can react with both acids and bases to produce salt and water. Such oxides are known as Amphoteric Oxides.
  Al2O3 + 6HCl → 2AlCl3 + H2O

• Metals also reacts with water to form metal oxide. Metal oxide in turn can react with water to form metal hydroxide. For Example

2Na + 2H₂O → 2NaOH + 1H₂

2Al + 3H₂O → Al₂O₃ + 3H₂

• Metals also reacts with dilute acids to form salt and hydrogen. For example, magnesium reacts with dilute hydrochloric acid to form magnesium chloride and hydrogen.

Metal + Acid → Metal Salt + Hydrogen

Mg + 2HCl → MgCl₂ + H₂

Chemical Properties of Non-metals-

• Non-metals reacts with oxygen to form non-metal oxide.

• Non-metal + Oxygen → Non-metal oxide

C + O₂ → CO₂

• Non-metals do not react with water and acids to evolve hydrogen gas.

• Non-metals can react with salt solution; more reactive element will displace the less reactive non-metal.

2 NaBr (aq) + Cl₂(aq) → 2NaCl (aq) + Br₂ (aq)

• Non-metals can also react with hydrogen to form hydrides.

H₂(g) + S(l) → H₂S(g)

Alloys

Alloys are homogeneous mixtures of metal with other metals or nonmetals. Alloy formation enhances the desirable properties of the material, such as hardness, tensile strength and resistance to corrosion.

Examples of a few alloys:
Brass: copper and zinc
Bronze: copper and tin
Solder: lead and tin
Amalgam: mercury and other metal

Reactivity Series-

The series in which metals are arranged in the decreasing order of reactivity, it is known as Reactivity Series.

Ionic Compounds-

Compounds formed due to the transfer of electrons from a metal to a non-metal are known as Ionic Compounds.

Covalent Bond

Bond formed by sharing of electrons between the two atoms. They share their valence electrons to gain stability.

Properties of Ionic Compounds-

• They are generally hard and solid.

• They have a high melting and boiling point.

• They are soluble in water but insoluble in inorganic solvents such as ether etc.

• They are conductors of electricity in molten and solution state.

Occurrence of Metals

Elements or compounds which occurs naturally in earth crust are known as Minerals. Minerals from which pure metals can be extracted are known as Mineral Ores

Extraction of pure metals from its ores/steps for extraction of metals from its ore-

• The first step is enrichment of the ore.

• Second step includes extraction of metals

• Third steps involve refining of metal

Gangue 

Ores contain different impurities in it such as sand, soil etc. These impurities are known as Gangue.

Extracting Metals which are low in activity series-

Metals which are low in activity series are unreactive. The oxides of such metals can be reduced to metals by heating alone. For Example, Cinnabar (HgS)

Extracting Metals in the middle of the Activity Series

These metals are moderately reactive. They exists as sulphides or carbonates in nature. Before reduction, metal sulphides and carbonates must be converted into metal oxides. Sulphide ores are converted into oxides by heating strongly in presence of excess air, this is known as Roasting. Carbonate ores are converted into oxides by heating in limited air. This is known as Calcination.

Roasting

Calcination

Extracting metals towards the top of the activity series-

The metals are highly reactive. They cannot be obtained by heating. For Example, Sodium, magnesium and calcium are obtained by the electrolysis of their molten chlorides.

At cathode  Na⁺ + e^– → Na At anode   2Cl^– → Cl₂ + 2e^–

Refining of Metals

Refining of impure metal is done using electrolytic refining. Impure copper is used as anode and strip of pure copper is used as Cathode. Acidified copper sulphate is used as electrolyte. When electric current is passed through this, impure metal from the anode gets deposited in the electrolyte solution, whereas pure metal from the electrolyte is deposited at cathode. Deposition of insoluble residue formed from the dissolution of anode during commercial electrolysis.

Carbon and its compound

Allotropes of Carbon

Different forms of an element that has same chemical properties but different physical properties are known as Allotropes. There are three allotropes of carbon- diamond, graphite and fullerene.

Diamond

Diamond exits as three-dimensional network with strong carbon-carbon covalent bonds. Diamond is hard in nature with high melting point.

It shines in presence of light and it is a bad conductor of electricity. The most common use of diamond is in making jewellery. It is also used in cutting and drilling tools.

Graphite

Graphite is made from weak van der wall forces. Each carbon atom is bonded with other three carbon atoms in order to form hexagonal rings. It serves as good conductor of heat and electricity. It is used as dry lubricant for machine parts as well as it is used in lead pencils.

Fullerene

It is a hollow cage which exits in the form of sphere. Its structure is similar to fullerene. But along with hexagonal rings, sometimes pentagonal or heptagonal rings are also present.

Two Important Properties of Carbon

• Catenation is a property of carbon by which carbon atoms can link one another via covalent bond and can form long chains, closed ring or branched chains etc. Carbon atoms can be linked by single, double or triple bonds.

• Carbon has a valency of 4 due to which it is known to have tetravalency. Due to this one carbon atom can bond with other 4 carbon atoms, with other atoms also such as Oxygen, Nitrogen etc.

Hydrocarbons

• Compounds which are made up of carbon and hydrogen they are known as Hydrocarbons.

• There are two types of hydrocarbons found  Saturated Hydrocarbons and Unsaturated Hydrocarbons.

• Saturated Hydrocarbons consist of single bonds between the carbon atoms. For Example, Alkanes. Alkanes are saturated hydrocarbons represented by a formula, C_nH_2n+2.

• Unsaturated Hydrocarbons are the one with double or triple bonds between the carbon atoms. For Example, Alkenes and Alkynes. Alkenes are represented as C_nH_2n whereas alkynes are represented as C_nH_2n-2. Some saturated hydrocarbons and unsaturated hydrocarbons are represented as –

Saturated hydrocarbons

Unsaturated hydrocarbons

Structure of hydrocarbons can be represented in the form of electron dot structure as well as open structures as shown below-

Carbons Compounds based on the basis of structure

Carbon Compounds can be classified as straight chain compounds, branched chain compounds and cyclic compounds. They are represented as

Straight chain carbon compound

Branched

Cyclic carbon compounds

Functional Groups

One of the hydrogen atoms in hydrocarbon can be replaced by other atoms according to their valencies. The atoms which decides the properties of the carbon atoms, are known as Functional Groups. For Example, Cl, Br, -OH, Aldehyde, Ketone, Carboxylic Acid etc.

Homologous Series

Series of compounds in which same functional group substitutes for the hydrogen atom in a chain of carbon.

Different functional groups

Chemical Properties of Carbon Compounds

Combustion

Carbon along with its compound is used as a fuel as it burns in presence of oxygen to release energy. Saturated hydrocarbons produce blue and non-sooty flame whereas unsaturated hydrocarbons produce yellow sooty flame.

CH₄ + 2O₂ → CO₂ + 2H₂O

Oxidation

Alcohol can be oxidized to aldehydes whereas aldehydes in turn can be oxidized to carboxylic acid. Oxidizing agent such as potassium permanganate can be used for oxidation.

Addition Reaction

Hydrogenation of vegetable oil is an example of addition reaction. Addition of hydrogen in presence of catalyst such as nickel or palladium. This converts oil into ghee.

Substitution Reaction

When one atom in hydrocarbon is replaced by chlorine, bromine, etc. this is known as Substitution Reaction.

• Cleansing Action of Soap-When soap is added to water, the soap molecules uniquely orient themselves to form spherical shape micelles.

The non-polar hydrophobic part or tail of the soap molecules attracts the dirt or oil part of the fabric, while the polar hydrophilic part or head,(−COO⁻Na⁺), remains attracted to water molecules.

The agitation or scrubbing of the fabric helps the micelles to carry the oil or dirt particles and detach them from the fibres of the fabric.

Hard Water

It contains salts of calcium and magnesium, principally as bicarbonates, chlorides, and sulphates. When soap is added to hard water, calcium and magnesium ions of hard water react with soap forming insoluble curdy white precipitates of calcium and magnesium salts of fatty acids. These precipitates stick to the fabric being washed and hence, interfere with the cleaning ability of the soap. Therefore, a lot of soap is wasted if the water is hard.

2C₁₇H₃₅COONa+MgCl₂ → (C₁₇H₃₅COO)₂Mg+2NaCl
2C₁₇H₃₅COONa+CaCl₂ → (C₁₇H₃₅COO)₂Ca+2NaCl

Ethanol

• Ethanol, C₂H₅OH is a colourless liquid having a pleasant smell.

• It boils at 351 K.

• It is ofmiscible with water in all proportions.

• It is a non-conductor  electricity (it does not contain ions)

• It is neutral to litmus.

Uses:

• As an antifreeze in radiators of vehicles in cold countries.

• As a solvent in the manufacture of paints, dyes, medicines, soaps and synthetic rubber.

• As a solvent to prepare the tincture of iodine.

How Do Alcohols Affect Human Beings?

• If ethanol is mixed with CH₃OH and consumed, it causes serious poisoning and loss of eyesight.

• It causes addiction, damages the liver if taken in excess.

• High consumption of ethanol may even cause death.

Reactions of Ethanol with Sodium-

Ethanol reacts with sodium to produce hydrogen gas and sodium ethoxide. This reaction supports the acidic character of ethanol.

2C₂H₅OH+2Na → 2C₂H₅ONa+H₂(↑)

Elimination Reaction

An elimination reaction is a type of reaction in which two substituents are removed from a molecule. These reactions play an important role in the preparation of alkenes.

Dehydration Reaction

Ethanol reacts with concentrated sulphuric acid at 443 K to produce ethylene. This reaction is known as dehydration of ethanol because, in this reaction, a water molecule is removed from the ethanol molecule.

CH₃CH₂OH → CH₂=CH₂+H₂O

(reaction taking place in presence of Conc.H₂SO₄)

Ethanoic Acid or Acetic

• Molecular formula: CH₃COOH

• It dissolves in water, alcohol and ether.

• It often freezes during winter in cold climate and therefore it is named as glacial acetic acid.

Esterification

When a carboxylic acid is refluxed with alcohol in the presence of a small quantity of conc.H₂SO₄, a sweet-smelling ester is formed. This reaction of ester formation is called esterification.

When ethanol reacts with ethanoic acid in presence of conc.H2SO4, ethyl ethanoate and water are formed.
CH₃COOH+C₂H₅OH → CH₃COOC₂H₅+H₂O

(reaction taking place in presence of Conc.H₂SO₄)

Saponification

A soap is a sodium or potassium salt of long-chain carboxylic acids (fatty acid). The soap molecule is generally represented as RCOONa, where R = non-ionic hydrocarbon group and  −COO⁻Na⁺ ionic group. When oil or fat of vegetable or animal origin is treated with a concentrated sodium or potassium hydroxide solution, hydrolysis of fat takes place; soap and glycerol are formed. This alkaline hydrolysis of oils and fats is commonly known as saponification.

Reaction of Ethanoic Acid with Metals and Bases-

Ethanoic acid (Acetic acid) reacts with metals like sodium, zinc and magnesium to liberate hydrogen gas.
2CH₃COOH+2Na→2CH₃COONa+H₂(↑)

It reacts with a solution of sodium hydroxide to form sodium ethanoate and water.
CH₃COOH+NaOH→CH₃COONa+H₂O

Reaction of Ethanoic Acid with Carbonates and Bicarbonates-

Carboxylic acids react with carbonates and bicarbonates with the evolution of CO₂ gas. For example, when ethanoic acid (acetic acid) reacts with sodium carbonate and sodium bicarbonate, CO₂ gas is evolved.
2CH₃COOH+Na₂CO₃→2CH₃COONa+H₂O+CO₂
CH₃COOH+NaHCO₃→CH₃COONa+H₂O+CO₂

Catenation-

Catenation is the self-linking property of an element by which an atom forms covalent bonds with the other atoms of the same element to form straight or branched chains and rings of different sizes. It is shown by carbon, sulphur and silicon.