Metals, Non-Metals & Alloys

Overview

Metals, non-metals, and alloys form a core area in UPSC General Science — questions appear on physical and chemical properties, the reactivity series, metallurgy, corrosion, and strategic minerals. This topic also links to GS-3 (economy/security) through rare earth elements and India's critical minerals policy.

Properties of Metals vs Non-Metals

Physical Properties

Chemical Properties

Metalloids (Semi-Metals)

Metalloids occupy the diagonal border between metals and non-metals in the periodic table. The commonly recognised metalloids are Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), and Tellurium (Te).

Comparison: Metals vs Non-Metals vs Metalloids

Reactivity Series of Metals

The reactivity series arranges metals in decreasing order of their tendency to lose electrons and react with other substances.

Key principles:

• A more reactive metal can displace a less reactive metal from its salt solution (single displacement reaction).
• Metals above hydrogen in the series react with dilute acids to release H₂ gas; those below hydrogen (Cu, Hg, Ag, Au, Pt) do not.
• The series also determines the extraction method: highly reactive metals (K to Al) require electrolysis; moderately reactive metals (Zn to Pb) are reduced with carbon/coke; low-reactivity metals (Cu, Hg) are obtained by roasting; and the least reactive (Ag, Au, Pt) occur free in nature.

Mnemonic for the reactivity series: King Nathan Came Mighty Along — Zealous Fellow Pb(Lead) Had Cups of Hg(Mercury) with Ag(Silver) and Au(Gold) and Pt(Platinum).

Metallurgy

Metallurgy is the process of extracting metals from their ores and refining them for use.

Common Ore Types

Steps in Metallurgy

Froth flotation — Used for sulphide ores; ore is mixed with water and pine oil; sulphide particles attach to oil-froth and float, while gangue sinks.

Thermite reaction — Fe₂O₃ + 2Al → 2Fe + Al₂O₃ — highly exothermic; used for welding railway tracks.

Electrolytic refining — The impure metal is made the anode, a thin strip of pure metal is the cathode, and acidified salt solution of the metal acts as the electrolyte. On passing current, pure metal deposits on the cathode while impurities settle as anode mud. This method is used for refining copper, zinc, tin, nickel, silver, and gold.

Corrosion and Its Prevention

Corrosion is the gradual destruction of metals by chemical or electrochemical reaction with the environment.

Types of Corrosion

Prevention Methods

Important Alloys

An alloy is a homogeneous mixture of a metal with one or more other metals or non-metals.

Why alloys? Pure metals are often too soft, too reactive, or lack desired properties. Alloying improves hardness, strength, corrosion resistance, or lowers melting point.

India's Major Mineral Resources

Noble Metals

Noble metals are found in free state in nature because they do not react easily with other elements.

Rare Earth Elements (REEs)

Strategic concern: Monazite sands also contain thorium (radioactive), which complicates mining and places it under atomic energy regulations.

Critical Minerals — India's Policy

UPSC Relevance

Prelims focus areas: Properties of metals vs non-metals, reactivity series order, alloy compositions (especially stainless steel, bronze, brass, duralumin), types of corrosion (uniform, galvanic, pitting), corrosion prevention methods, noble metals and aqua regia.

Mains and essay links (GS-3): Rare earth elements and India's strategic vulnerability, critical minerals for energy transition, China's dominance in REE supply chains (~70% mining, ~90% refining), KABIL and overseas mineral diplomacy (Argentina environmental clearance 2026; Chile ENAMI NDA), National Critical Minerals Mission (Rs 34,300 crore, 2025), MMDR Act amendment (private sector REE entry, March 2025), India's Japan REE export suspension (June 2025), India steel production FY26 (168.4 MT, 2nd globally), thorium reserves and India's three-stage nuclear programme.

Key terms to remember: Galvanisation, sacrificial anode, froth flotation, thermite reaction, Hall-Heroult process, aqua regia, monazite sands, anode mud, electrolytic refining, galvanic corrosion, pitting corrosion, stress corrosion cracking.

Common traps in Prelims:

• German silver contains no silver — it is Cu + Zn + Ni.
• Mercury is the only metal that is liquid at room temperature; bromine is a liquid non-metal.
• Graphite (a non-metal) conducts electricity — it is the key exception.
• Diamond has the highest hardness (10 on Mohs scale) among natural substances but is a poor conductor of electricity.
• Stainless steel contains chromium (minimum 10.5%), which forms a protective oxide layer — nickel is not always present in all grades.

Cross-paper relevance

• GS3 — General Science (primary) — Metal/non-metal properties, reactivity series, alloys; Prelims factual domain (critical minerals, rare earth elements, corrosion)
• GS3 — Economy — Critical minerals policy (India's Critical Minerals List 2023, 30 minerals), rare earth mining, battery supply chains for EVs; atmanirbharta in critical minerals
• GS2 — International Relations — China's dominance in rare earth supply chains; India-Australia critical minerals partnership; Minerals Security Partnership (MSP)
• Essay — "Critical minerals: the new battleground in the 21st-century technology race"

Recent Developments (2024–2026)

India Steel Production — Record 168.4 MT in FY 2025-26

India's crude steel output grew by 10.7% year-on-year to 168.4 million tonnes (MT) in FY 2025-26 (World Steel Association / JPC data). Finished steel consumption rose to 163.7 MT (FY 2025-26 — 2nd largest consumer globally after China). Steel exports of finished steel increased by 35.8% YoY in FY 2025-26. India retained its position as the world's second-largest steel producer (behind China, ~1,005 MT in 2024), accounting for approximately 7.9% of global crude steel production (up from 5.2% in 2014).

UPSC angle: FY26 headline fact: 168.4 MT crude steel production (+10.7%); 2nd largest producer globally; 163.7 MT finished steel consumption. Connects to infrastructure, Atmanirbhar Bharat, and PM Gati Shakti.

Critical Minerals Mission — India's Strategic Metals Policy (2024–25)

India launched the National Critical Minerals Mission (Cabinet approval 29 January 2025) with a total outlay of Rs 34,300 crore over seven years (2024-25 to 2030-31) — Rs 16,300 crore government expenditure plus Rs 18,000 crore PSU investment — for exploration, mining, processing, and recycling of 30 critical minerals. KABIL (Khanij Bidesh India Limited) received environmental clearance from the Argentine government (2026) to begin deep exploration of its 5 brine lithium blocks (15,703 hectares) in Catamarca province, India's $24 million (Rs 2 billion) exploration deal. KABIL has also filed expression of interest with Chile's ENAMI for lithium block exploration and is active in Australia for cobalt. In June 2025, IREL was asked by the government to suspend a 13-year-old REE export agreement with Japan to safeguard domestic supplies — a major policy signal on REE prioritisation. Private companies were officially allowed to explore and mine REEs from March 2025 (MMDR Act amendment), ending IREL's 75-year exclusive control.

UPSC angle: KABIL's Argentine environmental clearance (2026) is the latest field milestone; the Japan export suspension (June 2025) signals India's REE-for-domestic-use pivot; private sector entry into REE mining (March 2025, MMDR amendment) is a landmark policy change.

Lithium Reserves — India's Jammu & Kashmir Discovery

India's Geological Survey of India (GSI) confirmed inferred lithium reserves of 5.9 million tonnes in Reasi district, Jammu & Kashmir in February 2023 — a discovery whose strategic implications continued to be assessed and developed in 2024–25. Lithium is the key metal in Li-ion batteries powering electric vehicles and energy storage. India's goal of 30% EV penetration by 2030 makes domestic lithium supply critically important.

UPSC angle: J&K lithium reserves are a high-frequency Prelims fact (5.9 million tonnes, Reasi) and a Mains anchor for critical minerals, EV policy, and energy security questions.

Vocabulary

Malleable

• Pronunciation: /ˈmælɪəbəl/
• Definition: Capable of being hammered, pressed, or rolled into thin sheets without breaking — a characteristic physical property of most metals, with gold being the most malleable.
• Root: Latin malleus = hammer → malleāre = to hammer; Late Latin malleābilis; related to mallet, maul
• Origin: From Middle French malléable, from Late Latin malleābilis, from Latin malleāre (to hammer), from malleus (hammer); related to English mallet and maul.
• Part of Speech: adjective
• Word Family: malleability (n), malleably (adv), malleableness (n), mallet (n cognate)
• Usage: A robust democracy depends on institutions that are resilient rather than malleable, for once constitutional safeguards become malleable in the hands of a dominant executive, the rule of law quietly yields to the rule of expediency.
• Synonyms: pliable, ductile, pliant, adaptable, impressionable, tractable
• Antonyms: rigid, inflexible, intractable, obdurate
• Mnemonic: Think of a MALLET (a hammer) beating soft metal into shape - what the mallet can reshape is MALLEABLE. Both share the Latin root malleus, 'hammer'.

Ductile

• Pronunciation: /ˈdʌktaɪl/
• Definition: Capable of being drawn out into thin wire by mechanical force without breaking — a property exhibited by metals such as gold, silver, and copper.
• Root: Latin ductilis = that may be led or drawn; ductus (past participle of dūcere) = to lead, draw
• Origin: From Latin ductilis (that may be led or drawn), from ductus, past participle of dūcere (to lead or draw); first recorded in English in the 14th century.
• Part of Speech: adjective
• Word Family: ductility (n), ductilely (adv), ductileness (n), duct (n), deduct (v)
• Usage: A resilient democracy must remain ductile rather than brittle, bending to accommodate dissent and reform without fracturing its constitutional core under the pressures of social change.
• Synonyms: malleable, pliable, pliant, flexible, tractable, plastic
• Antonyms: brittle, rigid, inflexible, intractable
• Mnemonic: Think of a "duct" — a flexible pipe that can be drawn and bent into shape; like Latin ducere ('to lead/draw'), a ductile metal is led out into wire. A leader who can be led is "ductile".

Alloy

• Pronunciation: /ˈælɔɪ/
• Definition: A homogeneous metallic substance composed of two or more elements, at least one of which is a metal, combined to achieve improved properties such as hardness, strength, or corrosion resistance.
• Root: Latin ad- = to + ligāre = to bind → alligāre = to bind → Old French aloier = to combine metals
• Origin: From Old French aloi, from aloier (to combine), from Latin alligāre (to bind together); the sense of "mixture of metals" arose in the mid-17th century.

• Part of Speech: noun; verb (transitive)
• Word Family: alloy (n/v), alloyed (adj), alloying (v pres.p), unalloyed (adj)
• Usage: India's impressive headline growth is alloyed by persistent inequality and jobless expansion, a reminder that GDP figures alone cannot certify genuine development.
• Synonyms: amalgam, admixture, blend, composite, fusion; (as verb) adulterate, debase
• Antonyms: purify, refine, enhance; (noun sense) pure element
• Mnemonic: Root hook: alloy comes from Latin ligare 'to bind' (think ligament) — metals bound together. Sense hook: mix a little sorrow into ALL your JOY and the joy is alloyed (diminished); keep it pure and it is unalloyed.

Key Terms

Allotropes of Carbon

• Definition: Allotropes of carbon are the distinct structural forms in which the element carbon exists — such as diamond, graphite, fullerenes, graphene and carbon nanotubes — all made of identical carbon atoms but differing in bonding and atomic arrangement, which gives each form very different physical properties.
• Context: Carbon's capacity to form four covalent bonds and to bond extensively with itself (catenation) produces an unusually wide family of allotropes, ranging from the hardest natural substance (diamond) to one of the softest (graphite). The "nano" allotropes were discovered relatively recently: buckminsterfullerene (C60) was identified in 1985 (Nobel Prize in Chemistry 1996) and graphene was isolated in 2004 (Nobel Prize in Physics 2010). These materials are central to modern materials science, nanotechnology and electronics.
• UPSC Relevance: This is a foundational general-science concept that underpins UPSC Prelims questions on materials, nanotechnology and chemistry of carbon. Prelims commonly tests factual recall — which allotrope conducts electricity (graphite), which is the hardest (diamond), the dimensionality of graphene (2D) and the discovery/Nobel facts. For Mains GS3 (science and technology), the relevance lies in graphene and carbon nanotube applications — electronics, energy storage, composites — and India's policy push such as the India Innovation Centre for Graphene in Kerala. No verified direct PYQ is cited here; treat it as a foundation concept supporting the broader nanotechnology and new-materials theme.

Reactivity Series

• Pronunciation: /riːˌæktɪˈvɪti ˈsɪəriːz/
• Definition: An empirical ranking of metals in descending order of their tendency to lose electrons (undergo oxidation) and react with other substances such as water, acids, and metal salt solutions. The series runs from the most reactive metals (potassium, sodium, calcium) through moderately reactive metals (magnesium, aluminium, zinc, iron) to the least reactive noble metals (copper, silver, gold, platinum). It is used to predict displacement reactions (a more reactive metal displaces a less reactive metal from its salt solution) and to determine the most economical extraction method for each metal.
• Context: Built upon 19th-century electrochemistry experiments by Humphry Davy (isolated potassium and sodium by electrolysis, 1807) and Michael Faraday (laws of electrolysis, 1834). The key UPSC-relevant linkage is between reactivity and extraction method: highly reactive metals (K, Na, Ca, Al) are extracted by electrolysis of their molten ores (too reactive for carbon reduction); moderately reactive metals (Zn, Fe, Pb, Cu) are extracted by reduction with carbon/coke in blast furnaces; least reactive metals (Au, Pt, Ag) are found free in nature or extracted by simple methods. A more reactive metal can displace a less reactive one from solution -- e.g., iron displaces copper from copper sulphate solution (Fe + CuSO4 -> FeSO4 + Cu), which is the basis of copper purification.
• UPSC Relevance: GS3 (General Science / Economy). Prelims tests the order of reactivity (K > Na > Ca > Mg > Al > Zn > Fe > Ni > Sn > Pb > [H] > Cu > Hg > Ag > Au > Pt), which metals react with dilute acids (only those above hydrogen in the series), extraction methods linked to reactivity (electrolysis/carbon reduction/found free), and displacement reactions. Know common alloy compositions -- stainless steel (Fe + Cr + Ni, corrosion-resistant), bronze (Cu + Sn), brass (Cu + Zn), duralumin (Al + Cu + Mg + Mn, used in aircraft), solder (Pb + Sn), and that German silver contains NO silver (Cu + Zn + Ni) -- a perennial Prelims trap. Mains connects to India's Critical Minerals Mission (2025), rare earth elements strategy, and mineral resource management.

Corrosion

• Pronunciation: /kəˈrəʊʒən/
• Definition: The gradual destruction of a metal or alloy by chemical or electrochemical reaction with its environment, most commonly involving oxidation in the presence of moisture, oxygen, and electrolytes (such as dissolved salts). Rusting of iron (Fe2O3.xH2O, hydrated iron oxide) is the most common form, requiring both oxygen and water -- it does not occur in dry air alone or in water free of dissolved oxygen. Corrosion costs the global economy an estimated 3-4% of GDP annually in infrastructure damage and maintenance.
• Context: Prevention methods tested in UPSC: galvanisation (coating iron with zinc, which corrodes preferentially as a sacrificial anode), electroplating (depositing a thin layer of a less reactive metal), painting/oiling (barrier method preventing contact with moisture), alloying (stainless steel contains 12-18% chromium, which forms a passive oxide layer), cathodic protection (using sacrificial anodes of zinc or magnesium on ships and pipelines), and anodising (thickening the natural oxide layer on aluminium). Green patina on copper (CuCO3.Cu(OH)2, basic copper carbonate) and black tarnish on silver (Ag2S, silver sulphide) are other common corrosion examples. India's Ashoka Pillar in Delhi (Iron Pillar of Mehrauli, ~1,600 years old) is remarkable for its corrosion resistance, attributed to its high phosphorus content forming a protective misawite layer.
• UPSC Relevance: GS3 (General Science / Economy). Prelims tests conditions for rusting (both oxygen AND water required), prevention methods (galvanisation, painting, alloying, sacrificial anode/cathodic protection, anodising), green patina on copper (basic copper carbonate), and black tarnish on silver (silver sulphide). Know alloy compositions: stainless steel (Fe + Cr + Ni, corrosion-resistant due to chromium oxide layer), bronze (Cu + Sn), brass (Cu + Zn), duralumin (Al + Cu + Mg + Mn, used in aircraft). The Delhi Iron Pillar's corrosion resistance (high phosphorus content) is a favourite factoid. Mains connects to infrastructure maintenance costs, marine corrosion of naval assets, and India's critical minerals and metallurgy sector.

Sources: NCERT Class 10 Science (Chapter 3 — Metals and Non-Metals), USGS Rare Earths Statistics, PIB press releases (Critical Minerals List, June 2023; KABIL; National Critical Mineral Mission, January 2025), Mining Technology (China REE production data, 2025), Indian Bureau of Mines (Bauxite, Mica Yearbooks), US Naval Academy (Corrosion Types course notes), Wikipedia (Reactivity Series, Duralumin, Rare-earth element, Metalloid, Stainless Steel, Nickel Silver).