Core ConceptRead this first — the foundation of the topic
METALS & NON-METALS — CORE CONCEPT Metals and Non-Metals are two broad categories of elements. Understanding their properties and reactions is essential for RRB Group D Science.
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Metals are elements that are shiny, conduct electricity and heat, and can be beaten into sheets or drawn into wires. Non-Metals are elements that are generally dull, poor conductors, and brittle in solid form. About 80% of all elements in the periodic table are metals. Non-metals are found on the right side of the periodic table.
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Key RulesCore rules you must know cold
METALS:
- Lustrous (shiny surface)
- Hard and strong (except Na and K which are soft)
- Good conductors of heat and electricity
- Malleable — can be hammered into thin sheets (Gold is most malleable)
- Ductile — can be drawn into wires (Gold is most ductile; Silver is best conductor)
- High melting and boiling points (except Mercury — liquid at room temp; Gallium — melts in hand)
- Produce metallic sound when struck (Sonorous)
- Generally solid at room temperature (except Mercury)
NON-METALS:
- Non-lustrous (except Iodine and Diamond which are shiny)
- Poor conductors (except Graphite which conducts electricity)
- Brittle in solid form — cannot be hammered
- Low melting and boiling points (except Diamond — highest melting point)
- Non-sonorous
- Can be solid, liquid (Bromine), or gas at room temperature
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CHEMICAL REACTIONS OF METALS
With Oxygen: Metal + Oxygen → Metal Oxide (Basic in nature)
Example: 4Na + O2 → 2Na2O
With Water:
- Na and K react violently with cold water
- Mg reacts with hot water
- Fe reacts with steam only
- Cu, Au, Ag — do NOT react with water
With Acids: Metal + Dilute Acid → Salt + Hydrogen gas
Example: Zn + H2SO4 → ZnSO4 + H2
Non-metals form acidic oxides (e.g., SO2, CO2 dissolve in water to form acids).
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REACTIVITY SERIES (Important Order to Remember)
K > Na > Ca > Mg > Al > Zn > Fe > Ni > Sn > Pb > H > Cu > Hg > Ag > Au
Trick: King Narendra Can Make A Zinc Fence Now Since Police Have Caught Him Smoking Alcohol
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Exam PatternsWhat examiners ask — read before attempting PYQs
RRB Group D frequently asks:
- Which metal is liquid at room temperature? (Mercury)
- Which non-metal conducts electricity? (Graphite)
- Which metal is most malleable? (Gold)
- Which gas is produced when metal reacts with acid? (Hydrogen)
- Best conductor of electricity among metals? (Silver)
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SHORTCUT / TRICK
Trick 1 — Exceptions to remember (these are the MCQ traps):
- Mercury = metal + liquid at room temp
- Bromine = non-metal + liquid at room temp
- Graphite = non-metal + conducts electricity
- Iodine = non-metal + shiny/lustrous
- Sodium & Potassium = metals + very soft, stored in kerosene
- Diamond = non-metal + hardest natural substance + highest melting point
Trick 2 — Acid reaction memory: 'Metals above Hydrogen in reactivity series can displace H2 from dilute acids.' Copper, Silver, Gold CANNOT.
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Worked ExampleSolve this step-by-step before moving on
1
Step 1
Identify the type of reaction — Metal + Water (Steam)
Product is Iron (II,III) Oxide — Fe3O4 (black magnetic oxide) and Hydrogen gas.
Answer: Fe3O4 and Hydrogen gas (H2)
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Exam TrapsCommon mistakes students make — avoid these
Students confuse 'best conductor' with 'most malleable.' Silver is the BEST conductor of electricity. Gold is the MOST malleable and ductile. Do NOT mix these two up — this is a very common MCQ trap in RRB exams.
Key Points to Remember
Mercury is the only metal that is liquid at room temperature (melting point: -39°C).
Gold is the most malleable metal; Silver is the best conductor of electricity and heat.
Graphite (a form of Carbon — non-metal) is an exception that conducts electricity.
Metals form basic oxides; Non-metals form acidic oxides when reacting with oxygen.
Reactivity Series order: K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au.
Na and K are stored in kerosene because they react violently with air and water.
Bromine is the only non-metal that is liquid at room temperature.
Iron reacts with steam to form Fe3O4 (not FeO or Fe2O3) and hydrogen gas.
Exam-Specific Tips
Mercury (Hg) is the only metal in liquid state at room temperature; its melting point is -39°C.
Silver (Ag) is the best conductor of electricity among all metals.
Gold (Au) is the most malleable and ductile metal — 1g of gold can be beaten into 1 sq metre sheet.
Bromine (Br2) is the only non-metal that exists as a liquid at room temperature.
Graphite is the only non-metal (allotrope of Carbon) that conducts electricity.
Sodium (Na) and Potassium (K) are so reactive they are stored under kerosene oil.
Diamond is the hardest natural substance and has the highest melting point among non-metals.
Gallium (Ga) and Caesium (Cs) are metals that melt just above room temperature (~29-30°C).
Practice MCQs
Metals & Non-Metals — Practice Questions
12graded MCQs · easy to hard · full solution & trap analysis
Which of the following is a physical property that distinguishes metals from non-metals?
Practice 2easy
When a metal reacts with oxygen, it typically forms a/an:
Practice 3easy
Which element is a non-metal but conducts electricity in its solid state?
Practice 4easy
When a non-metal reacts with oxygen, the resulting compound is typically:
Practice 5medium
What is the general property of non-metals when exposed to heat?
Practice 6medium
Which of the following metals is the best conductor of electricity?
Practice 7medium
Which metal forms a protective oxide layer on its surface when exposed to air?
Practice 8medium
Which of the following is a non-metal that exists as a liquid at room temperature?
Practice 9medium
What happens when a metal reacts with oxygen to form a metal oxide?
Practice 10hard
A non-metal X forms an acidic oxide when burned in air. This oxide dissolves in water to produce an acidic solution. Which of the following could X be?
Practice 11hard
When a metal M reacts with dilute hydrochloric acid, it produces hydrogen gas. However, when the same metal is placed in a solution of copper sulfate, no reaction occurs. What can be concluded about the position of M in the reactivity series?
Practice 12hard
Which of the following metals exhibits the property of being malleable and ductile at room temperature, and is also the best conductor of electricity among all elements?
60-Second Revision — Metals & Non-Metals
Remember: Mercury = only liquid metal; Bromine = only liquid non-metal — top MCQ trap.
Remember: Silver = best conductor; Gold = most malleable/ductile — never mix these two.
Formula: Metal + Dilute Acid → Salt + H2 gas (metals above H in reactivity series only).
Formula: 3Fe + 4H2O(steam) → Fe3O4 + 4H2 — Iron reacts with STEAM only, not cold water.
Trap: Graphite conducts electricity — it is a NON-metal, not a metal.
Trick: Reactivity series mnemonic — King Narendra Can Make A Zinc Fence Now Since Police Have Caught Him Smoking Alcohol.
Remember: Na and K stored in kerosene; react violently with cold water releasing H2 gas.