Is it correct to say: Drawing all electrons of the atom in an electron-dot structure?

Only OUTERMOST (valence) electrons are shown as dots. Others are represented by the element symbol.

Is it correct to say: Writing NaCl as N a C l with no charges?

For the electron-dot version show the charges: Na⁺ and Cl⁻. Otherwise it looks covalent.

Is it correct to say: Saying 'all non-metals are gases'?

Non-metals may be solid (C, S, I₂), liquid (Br₂) or gas (H₂, O₂, N₂, noble gases).

Is it correct to say: Confusing malleability with ductility?

Malleable = can be beaten into thin sheets (gold foil). Ductile = can be drawn into wires (copper wire).

Is it correct to say: Assuming ionic compounds conduct electricity as solids?

Ionic solids do NOT conduct. Only in MOLTEN state or AQUEOUS solution — ions become free to move.

Is it correct to say: Calling graphite a metal because it conducts?

Graphite is a NON-METAL allotrope of carbon. Its delocalised π-electrons let it conduct — unique exception.

Metals and Non-Metals — Properties Focus

Physical properties, electron-dot structures, ionic vs covalent bonding of metals and non-metals — companion notes to NCERT Class 10 Chemistry Ch 3

📐 7 formulas✏️ 3 examples🎯 6 practice⚖️ 3-4 marks🏫 CBSE📚 Class 10✓ 2025–26 syllabus

💡

Board Exam Tips

→Electron-dot (Lewis) diagrams: draw dots for outermost electrons ONLY.
→Physical property comparison table (metal vs non-metal) is a favourite 3-mark question.
→Learn the exceptions in one line — Hg is liquid, iodine is lustrous, graphite conducts, diamond is hardest.
→Melting/boiling point trend — ionic compounds high, covalent low, metals mixed (Hg low, W very high).
→State one everyday application of each property (malleability → foil, ductility → wires, sonority → bells).

📐 Formulas(7)

Electron-Dot: Sodium Chloride★ Board fav

N a^{∙} +_{∙∙}^{∙∙} ∙∙ C l ∙∙^{∙} ⟶ N a^{+} [C l :]^{-}

Electron-Dot: Water

H : O ¨ : H

Electron-Dot: Methane

H : H C H : H

Reactivity Series (Compact)★ 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

Metal + Non-metal (Ionic)

2 N a + C l_{2} ⟶ 2 N a C l

Non-metal + Non-metal (Covalent)

H_{2} + C l_{2} ⟶ 2 H C l

Amphoteric Oxide Test

A l_{2} O_{3} + H C l, N a O H ⟶ both react

✏️ Solved Examples

1Solved Exampleeasy3 steps

Explain why sodium is stored in kerosene but copper is not.

Sodium is very high in the reactivity series — reacts vigorously with air and water

4 N a + O_{2} ⟶ 2 N a_{2} O; 2 N a + 2 H_{2} O ⟶ 2 N a O H + H_{2}

2Solved Exampleboard5 steps

Compare the physical properties of metals and non-metals in a five-row table (state, lustre, ductility, conductivity, sonority).

State: most metals solid; non-metals may be s/l/g. Exception: Hg (liquid metal), Br₂ (liquid non-metal).

3Solved ExampleHOTS4 steps

Metal X on burning in air forms a white oxide Y. Y is insoluble in water but dissolves both in HCl and NaOH. Identify X and Y and give equations.

Oxide dissolves in BOTH acid and base ⇒ amphoteric ⇒ Y is Al₂O₃ or ZnO.

⚠️ Traps & Common Mistakes

⚠️Common Mistakes6

1
Drawing all electrons of the atom in an electron-dot structure
✓Only OUTERMOST (valence) electrons are shown as dots. Others are represented by the element symbol.
2
Writing NaCl as N a C l with no charges
✓For the electron-dot version show the charges: Na⁺ and Cl⁻. Otherwise it looks covalent.
3
Saying 'all non-metals are gases'
✓Non-metals may be solid (C, S, I₂), liquid (Br₂) or gas (H₂, O₂, N₂, noble gases).
4
Confusing malleability with ductility
✓Malleable = can be beaten into thin sheets (gold foil). Ductile = can be drawn into wires (copper wire).
5
Assuming ionic compounds conduct electricity as solids
✓Ionic solids do NOT conduct. Only in MOLTEN state or AQUEOUS solution — ions become free to move.
6
Calling graphite a metal because it conducts
✓Graphite is a NON-METAL allotrope of carbon. Its delocalised π-electrons let it conduct — unique exception.

🎯 Practice Yourself

🎯Practice Yourself6 questions

Q1
Which non-metal is (a) lustrous, (b) a good conductor of electricity, (c) liquid at room temperature?
Q2
State two reasons why aluminium is used to make cooking utensils.
Q3
Give one example of each: (a) an amphoteric oxide, (b) a neutral oxide, (c) an acidic oxide.
Q4
Why does an ionic compound like NaCl conduct electricity when dissolved in water?
Q5
Draw the electron-dot structure of MgO.
Q6
Why is tungsten used for filaments of electric bulbs?

📝 Notes

Metals and Non-Metals — Properties Focus

Companion notes to Chapter 3 with emphasis on physical properties and bonding. For extraction/reactivity details see the separate note Metals and Non-Metals (metals-nonmetals).

Physical property quick-look

| Property | Metals | Non-metals | |---|---|---| | State (RT) | Solid (Hg is liquid) | s/l/g (Br₂ liquid) | | Lustre | Shiny | Dull (I₂ lustrous) | | Malleable | Yes | No (brittle) | | Ductile | Yes | No | | Conductor | Yes | No (graphite exception) | | Sonorous | Yes | No | | Density | High (Li, Na low) | Low | | Melting point | High (Hg low) | Low (C, Si high) |

Chemical properties in one line

Metals lose electrons → CATIONS → REDUCING agents → basic oxides.
Non-metals gain electrons → ANIONS → OXIDISING agents → acidic oxides.
Amphoteric oxides (Al₂O₃, ZnO, PbO) fit neither category.

Ionic vs covalent bond

Metal + non-metal → transfer → ionic (NaCl, MgO, CaF₂).
Non-metal + non-metal → sharing → covalent (H₂O, CH₄, CO₂).

Everyday applications of the physical properties

Malleable Au, Ag → foils, ornaments.
Ductile Cu, Al → electrical wires.
Sonorous → bells and coins.
Good thermal conductor → cooking utensils (Al, Cu, stainless steel).
Reflective → mirrors (thin Ag / Al film).

Quick sanity checks

Only ionic solids in MOLTEN/AQUEOUS state conduct. Covalent + solid ionic do NOT.
Metals give MORE than 4 electrons? Usually noble/transition — check block position.
Non-metals shown in electron-dot with LONE pairs — do not forget them.