9. Chemistry of Non-metals
Non-metals are a group of elements that typically lack metallic properties such as luster, conductivity, and malleability. They play crucial roles in countless chemical reactions and form the basis of organic and inorganic compounds essential for life.
9.1 Hydrogen
Hydrogen (H) is the lightest and most abundant element in the universe. It's a key component of water and organic molecules.
- 9.1.1 Chemistry of atomic and nascent hydrogen: Atomic hydrogen is highly reactive due to its single electron. Nascent hydrogen refers to hydrogen freshly generated in a reaction, exhibiting higher reactivity than molecular hydrogen due to its atomic form.
- 9.1.2 Isotopes of hydrogen and their uses: Hydrogen has three main isotopes:
- Protium (^1H): Most common, no neutrons.
- Deuterium (^2H or D): One neutron, used in nuclear reactors (heavy water) and as a tracer.
- Tritium (^3H or T): Two neutrons, radioactive, used in luminous paints and as a tracer in biological studies.
- 9.1.3 Application of hydrogen as fuel: Hydrogen is a clean fuel, producing only water upon combustion. It's used in fuel cells to generate electricity, offering a promising alternative for transportation and energy storage.
- 9.1.4 Heavy water and its applications: Heavy water (D^2O) is water composed of deuterium instead of protium. It's used as a neutron moderator in nuclear reactors and as a solvent in NMR spectroscopy.
9.2 Allotropes of Oxygen
Oxygen (O) is a highly reactive non-metal, crucial for respiration and combustion.
- 9.2.1 Definition of allotropy and examples: Allotropy is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes. Examples include oxygen (O^2, O^3), carbon (diamond, graphite, fullerenes), and sulfur.
- 9.2.2 Oxygen: Types of oxides: Oxides are compounds formed with oxygen.
- Acidic oxides: Non-metal oxides (e.g., CO^2, SO^2), react with water to form acids.
- Basic oxides: Metal oxides (e.g., Na^2O, CaO), react with water to form bases.
- Neutral oxides: Do not react with acids or bases (e.g., CO, N^2O).
- Amphoteric oxides: React with both acids and bases (e.g., Al^2O^3, ZnO).
- Peroxides: Contain the O^2^2- ion (e.g., H^2O^2, Na^2O^2).
- Mixed oxides: Composed of two different oxides of the same metal (e.g., Pb^3O^4).
- 9.2.3 Applications of hydrogen peroxide: H^2O^2 is a strong oxidizing agent used as an antiseptic, bleaching agent, and in rocket propulsion.
- 9.2.4 Medical and industrial application of oxygen: Oxygen is vital for medical treatments (respiratory support), steel production, welding, and in various chemical processes.
9.3 Ozone
Ozone (O^3) is an allotrope of oxygen with a distinct pungent odor.
- 9.3.1 Occurrence: Occurs naturally in the stratosphere (ozone layer) and also formed in the troposphere as a pollutant.
- 9.3.2 Preparation of ozone from oxygen: Ozone is prepared by passing silent electric discharge through dry oxygen in an ozonizer: 3O^2(g) -> 2O^3(g).
- 9.3.3 Structure of ozone: Ozone has a bent structure with a bond angle of approximately 117 degrees and delocalized pi electrons, resulting in resonance.
- 9.3.4 Test for ozone: Ozone turns potassium iodide (KI) starch paper blue-black due to the oxidation of I^- to I^2, which then reacts with starch.
- 9.3.5 Ozone layer depletion (causes, effects and control measures):
- Causes: Primarily chlorofluorocarbons (CFCs), halons, and other ozone-depleting substances.
- Effects: Increased UV radiation reaching Earth's surface, leading to skin cancer, cataracts, and harm to ecosystems.
- Control measures: International agreements like the Montreal Protocol to phase out ODS production.
- 9.3.6 Uses of ozone: Used as a disinfectant for water purification, bleaching agent, and in the synthesis of organic compounds.
9.4 Nitrogen
Nitrogen (N) is a relatively inert gas, making up about 78% of Earth's atmosphere.
- 9.4.1 Reason for inertness of nitrogen and active nitrogen: Nitrogen's inertness is due to the strong triple bond (N≡N) that requires a large amount of energy to break. Active nitrogen refers to highly reactive atomic nitrogen, formed at high temperatures or by electrical discharge.
- 9.4.2 Chemical properties of ammonia (NH^3):
- Action with CuSO^4 solution: Forms a deep blue complex, [Cu(NH^3)^4]^2+.
- Action with water: Forms ammonium hydroxide (NH^4OH), a weak base.
- Action with FeCl^3 solution: Forms reddish-brown precipitate of iron(III) hydroxide.
- Action with Conc. HCl: Forms dense white fumes of ammonium chloride.
- Action with Mercurous nitrate paper: Turns black due to the formation of finely divided mercury.
- Action with O^2: Burns to form nitrogen and water, or with a catalyst, nitric oxide.
- 9.4.3 Applications of ammonia: Used in fertilizers, refrigerants, and the production of nitric acid and other nitrogen compounds.
- 9.4.4 Harmful effects of ammonia: Highly irritating to eyes, skin, and respiratory tract. High concentrations can be fatal.
- 9.4.5 Oxy-acids of nitrogen:
- Nitrous acid (HNO^2)
- Nitric acid (HNO^3)
- 9.4.6 Chemical properties of nitric acid (HNO^3) as an acid and oxidizing agent:
- As an acid: Reacts with bases to form salts and water.
- As an oxidizing agent: The products depend on the concentration of HNO^3 and the reducing agent.
- With zinc: Dilute HNO^3 forms NH^4NO^3, concentrated HNO^3 forms NO^2.
- With magnesium: Very dilute HNO^3 forms H^2.
- With iron: Passivates iron with concentrated HNO^3.
- With copper: Dilute HNO^3 forms NO, concentrated HNO^3 forms NO^2.
- With sulfur: Oxidizes to H^2SO^4.
- With carbon: Oxidizes to CO^2.
- With SO^2: Oxidizes to H^2SO^4.
- With H^2S: Oxidizes to sulfur.
- 9.4.7 Ring test for nitrate ion: A brown ring forms at the junction of concentrated H^2SO^4 and a solution containing nitrate ions, ferrous sulfate, and the sample, due to the formation of a nitroso-ferrous complex, [Fe(NO)(H^2O)^5]^2+.
9.5 Halogens
Halogens (Group 17) are highly reactive non-metals, including fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
- 9.5.1 General characteristics of halogens: High electronegativity, high electron affinity, form -1 ions, strong oxidizing agents (oxidizing power decreases down the group), generally colored.
- 9.5.2 Comparative study on preparation, chemical properties and uses of Cl^2, Br^2 and I^2:
- Preparation: Typically from halide salts by oxidation. (e.g., MnO^2 + 4HCl -> MnCl^2 + 2H^2O + Cl^2).
- Chemical properties:
- With water: Reacts to form hydrohalic acid and hypohalous acid (e.g., Cl^2 + H^2O <=> HCl + HOCl).
- With alkali: Forms halides and hypohalites (cold, dilute) or halates (hot, concentrated).
- With ammonia: Forms ammonium halides or nitrogen gas.
- Oxidizing character: Decreases down the group (Cl^2 > Br^2 > I^2). Each halogen can oxidize the halide ions of the halogens below it.
- Bleaching action: Chlorine and bromine act as bleaching agents by oxidation.
- Uses: Chlorine for water disinfection, PVC production. Bromine for flame retardants, pharmaceuticals. Iodine for antiseptics, thyroid health.
- 9.5.3 Test for Cl^2, Br^2 and I^2:
- Cl^2: Turns moist blue litmus paper red, then bleaches it.
- Br^2: Brownish-red vapor, turns starch paper yellowish-brown.
- I^2: Violet vapor, turns starch paper blue-black.
- 9.5.4 Comparative study on preparation, properties and uses of haloacids (HCl, HBr and HI):
- Preparation: Typically by direct synthesis or reaction of metal halides with a non-volatile acid.
- Properties:
- Reducing strength: Increases down the group (HCl < HBr < HI). HI is a strong reducing agent.
- Acidic nature: Increases down the group (HCl < HBr < HI) due to decreasing bond strength.
- Solubility: Highly soluble in water.
- Uses: HCl is a strong acid used in industry. HBr and HI are used in organic synthesis.
9.6 Carbon
Carbon (C) is a versatile element forming the backbone of organic chemistry.
- 9.6.1 Allotropes of carbon (crystalline and amorphous) including fullerenes:
- Crystalline: Diamond (hardest known substance, tetrahedral), Graphite (soft, lubricant, hexagonal layers), Fullerenes (e.g., C^60 buckyball, hollow sphere).
- Amorphous: Coal, coke, charcoal, lampblack.
- Fullerenes (structure, general properties and uses only): Cage-like or tube-like structures. Properties include high strength, conductivity, and unique reactivity. Uses in medicine, nanotechnology, and materials science.
- 9.6.2 Properties and uses of carbon monoxide (CO):
- Properties: Colorless, odorless, highly toxic gas. Acts as a reducing agent (e.g., in extraction of metals). Reacts with metals to form metal carbonyls.
- Uses: Fuel gas, reducing agent in metallurgy, in the synthesis of organic compounds.
9.7 Phosphorus
Phosphorus (P) is an essential element found in DNA, RNA, and ATP.
- 9.7.1 Allotropes of phosphorus (name only): White phosphorus, Red phosphorus, Black phosphorus.
- 9.7.2 Preparation, properties and uses of phosphine (PH^3):
- Preparation: (No diagram/description) Usually from the reaction of metal phosphides with water or acids.
- Properties: Highly poisonous, colorless gas with a rotten fish smell.
- Basic nature: Weakly basic, forms phosphonium salts (e.g., PH^4I).
- Reducing nature: Strong reducing agent, burns in air.
- Action with halogens: Reacts vigorously.
- Action with oxygen: Ignites spontaneously in air (impure PH^3).
- Uses: In Holme's signals (smoke screens), and as a fumigant.
9.8 Sulphur
Sulphur (S) is a yellow non-metal found in various compounds and allotropic forms.
- 9.8.1 Allotropes of sulphur (name only) and uses of sulphur: Rhombic (alpha) sulphur, Monoclinic (beta) sulphur, Plastic sulphur. Uses: production of sulphuric acid, vulcanization of rubber, fungicides, gunpowder.
- 9.8.2 Hydrogen sulphide (H^2S):
- Preparation from Kipp's apparatus: Iron sulfide (FeS) reacts with dilute sulfuric acid (H^2SO^4) or hydrochloric acid (HCl) to produce H^2S gas. FeS + 2HCl -> FeCl^2 + H^2S(g).
- Properties: Colorless, highly poisonous gas with a rotten egg smell.
- Acidic nature: Weak dibasic acid.
- Reducing nature: Strong reducing agent, readily oxidized to sulfur.
- Analytical reagent: Used to precipitate metal sulfides (qualitative analysis).
- Uses: In qualitative analysis, as a reducing agent.
- 9.8.3 Sulphur dioxide (SO^2) its properties and uses:
- Properties: Colorless gas with pungent smell.
- Acidic nature: Forms sulfurous acid (H^2SO^3) with water.
- Reducing nature: Acts as a reducing agent in the presence of strong oxidizing agents.
- Oxidizing nature: Acts as an oxidizing agent with strong reducing agents.
- Bleaching action: Bleaches by reduction, temporary.
- Uses: In production of H^2SO^4, bleaching wool and silk, preservative.
- 9.8.4 Sulphuric acid (H^2SO^4) and its properties and uses:
- Properties: Strong mineral acid, corrosive.
- Acidic nature: Strong dibasic acid.
- Oxidising nature: Strong oxidizing agent, especially when hot and concentrated.
- Dehydrating nature: Strong dehydrating agent, removes water from organic compounds.
- Uses: Most produced chemical, used in fertilizers, detergents, dyes, petroleum refining, and car batteries.
- 9.8.5 Sodium thiosulphate (formula and uses): Formula: Na^2S^2O^3. Uses: In photography (hypo), as an antichlor, in volumetric analysis (iodometry), and medical treatment for cyanide poisoning.
10. Chemistry of Metals
Metals are elements characterized by their luster, malleability, ductility, and good electrical and thermal conductivity. They play vital roles in industry, technology, and biological systems.
10.1 Metals and Metallurgical Principles
Metallurgy is the science and technology of extracting metals from their ores and refining them for use.
- 10.1.1 Definition of metallurgy and its types:
- Metallurgy: The process of extracting metals from their ores and modifying them into useful forms.
- Hydrometallurgy: Uses aqueous solutions to extract metals.
- Pyrometallurgy: Uses high temperatures for extraction.
- Electrometallurgy: Uses electrochemical processes (electrolysis).
- 10.1.2 Introduction of ores: An ore is a naturally occurring solid material from which a metal or valuable mineral can be extracted profitably.
- 10.1.3 Gangue or matrix, flux and slag, alloy and amalgam:
- Gangue/Matrix: The unwanted rocky material associated with the ore.
- Flux: A substance added during smelting to remove impurities (gangue) by forming a fusible product.
- Slag: The fusible product formed from the reaction of flux with gangue.
- Alloy: A mixture of two or more metals, or a metal and a non-metal, to enhance properties.
- Amalgam: An alloy of mercury with another metal.
- 10.1.4 General principles of extraction of metals:
- Concentration: Removal of gangue from the ore (e.g., froth flotation, magnetic separation, gravity separation).
- Calcination: Heating an ore strongly in the absence of air (e.g., carbonate ores decompose).
- Roasting: Heating an ore strongly in the presence of air (e.g., sulfide ores convert to oxides).
- Smelting: Melting an ore to separate the metal from other impurities, usually in a furnace.
- Carbon reduction: Reduction of metal oxides using carbon or CO (e.g., Fe^2O^3 + 3CO -> 2Fe + 3CO^2).
- Thermite reduction: Highly exothermic reaction where a metal oxide is reduced by a more reactive metal (e.g., Al).
- Electrochemical reduction: Electrolysis used for highly reactive metals (e.g., Na, Al).
- 10.1.5 Refining of metals:
- Poling: Used for metals containing oxides as impurities (e.g., copper). Green wood poles are stirred into the molten metal.
- Electro-refinement: Most common method for high purity. Impure metal acts as anode, pure metal as cathode, and a salt solution as electrolyte.
10.2 Alkali Metals
Alkali metals (Group 1) are highly reactive metals with one valence electron.
- 10.2.1 General characteristics of alkali metals: Low ionization energy, low electronegativity, highly reactive, form +1 ions, soft, low melting points, strong reducing agents.
- 10.2.2 Sodium (Na):
- Extraction from Down's process: Electrolysis of molten sodium chloride (NaCl) with calcium chloride (CaCl^2) to lower melting point.
- Properties:
- Action with Oxygen: Forms sodium oxide (Na^2O), peroxide (Na^2O^2), or superoxide (NaO^2).
- Action with water: Vigorous reaction, producing hydrogen gas and sodium hydroxide.
- Action with acids: Explodes, forming hydrogen gas and sodium salt.
- Action with nonmetals: Reacts readily (e.g., with Cl^2 to form NaCl).
- Action with ammonia: Forms sodamide (NaNH^2) and hydrogen.
- Uses: Coolant in nuclear reactors, street lamps, production of other chemicals.
- 10.2.3 Properties and uses of sodium hydroxide (NaOH):
- Properties: Strong base, deliquescent.
- Precipitation reaction: Precipitates hydroxides of many metal ions (e.g., FeCl^3 + 3NaOH -> Fe(OH)^3 + 3NaCl).
- Action with carbon monoxide: Forms sodium formate at high temperature and pressure.
- Uses: Soap and detergent manufacturing, paper industry, refining petroleum.
- 10.2.4 Properties and uses of sodium carbonate (Na^2CO^3):
- Properties: White solid, soluble in water, forms an alkaline solution due to hydrolysis.
- Action with CO^2: Forms sodium bicarbonate (NaHCO^3).
- Action with SO^2: Forms sodium sulfite (Na^2SO^3).
- Action with water: Dissolves to give an alkaline solution.
- Precipitation reactions: Precipitates carbonates of many metal ions.
- Uses: Glass manufacturing, soap and detergent production, water softening.
10.3 Alkaline Earth Metals
Alkaline earth metals (Group 2) are reactive metals with two valence electrons.
- 10.3.1 General characteristics of alkaline earth metals: Less reactive than alkali metals, higher melting points, form +2 ions, good reducing agents (reducing power increases down the group).
- 10.3.2 Molecular formula and uses of specific compounds:
- Quick lime: CaO, used in cement, steel production.
- Bleaching powder: CaOCl^2, used as a bleaching agent and disinfectant.
- Magnesia: MgO, used as refractory material, antacid.
- Plaster of Paris: CaSO^4.0.5H^2O, used in casts, sculptures.
- Epsom salt: MgSO^4.7H^2O, used as a laxative, bath salts.
- 10.3.3 Solubility of hydroxides, carbonates and sulphates of alkaline earth metals (general trend with explanation):
- Hydroxides: Solubility increases down the group (Be(OH)^2 is least soluble, Ba(OH)^2 is most soluble) due to increasing ionic character and decreasing lattice energy relative to hydration energy.
- Carbonates: Solubility decreases down the group (BeCO^3 most soluble, BaCO^3 least soluble) due to decreasing hydration energy and relatively stable lattice energy.
- Sulphates: Solubility decreases down the group (BeSO^4 most soluble, BaSO^4 least soluble) due to the large size of the sulfate ion, making lattice energy more dominant than hydration energy as cation size increases.
- 10.3.4 Stability of carbonate and nitrate of alkaline earth metals (general trend with explanation): Thermal stability increases down the group. Larger cations can stabilize larger anions more effectively, so BaCO^3 and Ba(NO^3)^2 are more stable to heat than BeCO^3 and Be(NO^3)^2.
11. Bio-inorganic Chemistry
Bio-inorganic chemistry explores the roles of metals in biological systems, encompassing essential functions and toxic effects.
11.1 Introduction to Bio-inorganic Chemistry
This field bridges inorganic chemistry and biology, focusing on the interactions of metal ions with biomolecules.
- 11.1 Introduction: Understanding how metal ions contribute to the structure and function of proteins, enzymes, and other biological systems.
- 11.2 Micro and macro nutrients:
- Macronutrients: Required in larger quantities (e.g., Na, K, Mg, Ca, P, S, Cl).
- Micronutrients (trace elements): Required in smaller quantities (e.g., Fe, Cu, Zn, Mn, I, Se, Mo, Cr, Co, B).
- 11.3 Importance of metal ions in biological systems:
- Na, K: Nerve impulse transmission, fluid balance (sodium-potassium pump).
- Mg: Cofactor for enzymes, chlorophyll structure, bone health.
- Ca: Bone and tooth structure, muscle contraction, blood clotting.
- Fe: Oxygen transport (hemoglobin), electron transfer (cytochromes).
- Cu: Enzyme cofactor (cytochrome c oxidase), collagen formation.
- Zn: Enzyme cofactor (carbonic anhydrase), immune function, wound healing.
- Ni: Cofactor in urease enzyme.
- Co: Component of Vitamin B12.
- Cr: Glucose metabolism.
- 11.4 Ion pumps (sodium-potassium and sodium-glucose pump):
- Sodium-potassium pump: An active transport system that pumps 3 Na^+ ions out of the cell and 2 K^+ ions into the cell, maintaining electrochemical gradients essential for nerve impulses and muscle contraction.
- Sodium-glucose pump: A co-transport system that moves glucose into the cell by utilizing the electrochemical gradient created by the sodium-potassium pump.
- 11.5 Metal toxicity (toxicity due to iron, arsenic, mercury, lead and cadmium): Excess or inappropriate forms of metal ions can be toxic.
- Iron (Fe): Hemochromatosis, oxidative stress.
- Arsenic (As): Carcinogenic, interferes with cellular respiration.
- Mercury (Hg): Neurotoxic, affects kidneys and brain.
- Lead (Pb): Neurotoxic, affects cognitive development, causes anemia.
- Cadmium (Cd): Carcinogenic, causes kidney damage and bone demineralization.