Is it correct to say: Believing all metals react with acids?

Only metals above H in the activity series do. Cu, Ag, Au do NOT react with dilute HCl.

Is it correct to say: Mixing up roasting and calcination?

Roasting = sulphide + excess air. Calcination = carbonate/hydrated oxide in limited/no air.

Is it correct to say: Using carbon reduction for aluminium?

Al is too reactive for C reduction. Extracted by electrolysis of molten Al_2O_3 in cryolite.

Is it correct to say: Writing 'rusting' equation without water?

Rusting requires BOTH O_2 and H_2O. Iron in dry air or boiled distilled water alone does not rust.

Is it correct to say: Calling all metal oxides basic?

Al_2O_3, ZnO are amphoteric (react with both acid and base). Most non-metal oxides are acidic.

Is it correct to say: Thinking galvanised iron loses protection when the zinc coat scratches?

Even scratched, Zn continues to protect iron sacrificially — Zn > Fe in the series, so Zn corrodes first.

Metallurgy — Metals and Non-metals

Activity series, extraction of metals, corrosion, alloys, ionic bonding — Maharashtra SSC Science Part 1 Ch 8

📐 12 formulas✏️ 3 examples🎯 6 practice⚖️ 5-6 marks🏫 Maharashtra State Board📚 Class 10✓ 2025–26 syllabus

💡

Board Exam Tips

→Activity series K > Na > Ca > Mg > Al > Zn > Fe > Pb > (H) > Cu > Hg > Ag > Au must be memorised — used in every displacement/extraction question.
→Extraction depends on position in activity series: top → electrolysis, middle → reduction, bottom → heat alone.
→Marathi: धातू (metal), अधातू (non-metal), धातुविज्ञान (metallurgy), भर्जन (roasting), निस्तापन (calcination).
→Thermite reaction (Fe_2O_3 + 2Al) and its use in welding is a 3-mark favourite.
→Corrosion prevention (galvanising, painting, oiling, alloying, cathodic protection) — list 3 methods for 3 marks.

📐 Formulas(12)

Reactivity Series (Descending)★ Board fav

K > N a > C a > M g > A l > Z n > F e > P b > H > C u > H g > A g > A u

Formation of Ionic Bond

N a + C l \to N a^{+} + C l^{-} \to N a C l

Metal + Oxygen

4 N a + O_{2} \to 2 N a_{2} O

Metal + Acid★ Board fav

Metal + 2 H C l \to Metal chloride + H_{2} ↑

Metal Displacement in Solution

F e + C u S O_{4} \to F e S O_{4} + C u

Roasting (Sulphide Ore)★ Board fav

2 Z n S + 3 O_{2} Δ 2 Z n O + 2 S O_{2}

Calcination (Carbonate Ore)

Z n C O_{3} Δ Z n O + C O_{2}

Reduction of Oxide by Carbon

Z n O + C Δ Z n + C O

Electrolytic Reduction (for K, Na, Ca, Mg, Al)

At cathode: M^{n +} + n e^{-} \to M

Rusting of Iron

4 F e + 3 O_{2} + x H_{2} O \to 2 F e_{2} O_{3} \cdot x H_{2} O

Amphoteric Oxide (Al_2O_3)

A l_{2} O_{3} + 6 H C l \to 2 A l C l_{3} + 3 H_{2} O; A l_{2} O_{3} + 2 N a O H \to 2 N a A l O_{2} + H_{2} O

Thermite Reaction★ Board fav

F e_{2} O_{3} + 2 A l \to 2 F e + A l_{2} O_{3} + heat

✏️ Solved Examples

1Solved Exampleeasy2 steps

Arrange in decreasing order of reactivity: Cu, Fe, Zn, Mg.

Recall the activity series

K > N a > C a > M g > A l > Z n > F e > P b > H > C u > H g > A g > A u

2Solved Exampleboard3 steps

Copper articles gradually turn green when exposed to moist air. Write the balanced equation and name the product.

Moist air contains CO_2 and O_2

3Solved ExampleHOTS3 steps

Zinc is extracted from its sulphide ore. Give the balanced equations of the two steps involved and explain why roasting and not calcination is used.

Step 1 — Roasting (sulphide + excess O_2)

2 Z n S + 3 O_{2} Δ 2 Z n O + 2 S O_{2}

⚠️ Traps & Common Mistakes

⚠️Common Mistakes6

1
Believing all metals react with acids
✓Only metals above H in the activity series do. Cu, Ag, Au do NOT react with dilute HCl.
2
Mixing up roasting and calcination
✓Roasting = sulphide + excess air. Calcination = carbonate/hydrated oxide in limited/no air.
3
Using carbon reduction for aluminium
✓Al is too reactive for C reduction. Extracted by electrolysis of molten Al_2O_3 in cryolite.
4
Writing 'rusting' equation without water
✓Rusting requires BOTH O_2 and H_2O. Iron in dry air or boiled distilled water alone does not rust.
5
Calling all metal oxides basic
✓Al_2O_3, ZnO are amphoteric (react with both acid and base). Most non-metal oxides are acidic.
6
Thinking galvanised iron loses protection when the zinc coat scratches
✓Even scratched, Zn continues to protect iron sacrificially — Zn > Fe in the series, so Zn corrodes first.

🎯 Practice Yourself

🎯Practice Yourself6 questions

Q1
Why is sodium stored under kerosene?
Q2
State two properties which show that gold is less reactive.
Q3
Write balanced equation for reaction of Mg with dilute HCl.
Q4
Which ore is called bauxite? Give its formula.
Q5
Give three methods to prevent rusting of iron.
Q6
State one use each of copper, aluminium and gold.

📝 Notes

Metallurgy — Metals and Non-metals

Metals form the backbone of civilisation — from copper coins to aluminium aircraft. This chapter connects physical properties (lustre, ductility, conductivity) with chemical behaviour (reactivity, extraction, corrosion).

SSC angle

Chapter 8 of Science Part 1 commonly asks:

2-mark: three physical or chemical differences between metals and non-metals.
3-mark: flowchart of Zn or Cu extraction — mention roasting, reduction, refining.
4-mark: activity series with extraction method table + thermite reaction.

Physical properties — quick contrast

| Property | Metals | Non-metals | |---|---|---| | Lustre | Shiny | Dull (except I_2) | | Malleability | Yes | No (brittle) | | Ductility | Yes | No | | Conductivity | Good | Poor (except graphite) | | Melting point | High | Low | | State (room T) | Solid (except Hg) | Solid/liquid/gas |

Extraction method — pick by activity

Top (K, Na, Ca, Mg, Al): electrolysis of molten chloride/oxide.
Middle (Zn, Fe, Pb, Cu): roast/calcine, then carbon reduction.
Bottom (Ag, Au, Pt): occur native, or thermal decomposition of oxide.

Refining methods

Electrolytic refining: impure metal = anode, pure = cathode. Used for Cu, Zn, Al.
Distillation: low-boiling metals like Hg, Zn.
Liquation: for low-melting Sn, Pb.

Alloys quick list

| Alloy | Composition | Use | |---|---|---| | Brass | Cu + Zn | Utensils | | Bronze | Cu + Sn | Statues, medals | | Steel | Fe + C | Construction | | Stainless steel | Fe + Cr + Ni | Cutlery | | Solder | Pb + Sn | Joining wires | | Amalgam | Metal + Hg | Dental filling |

Alloys resist corrosion, are harder, look better and often melt at lower temperatures than pure metals.

Board vs CBSE

Content overlaps considerably. Maharashtra SSC gives extra weight to the reactivity series and extraction flow charts — practise labelling every step with the correct reaction.