Chapter 9 of 23

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Tamil Nadu (TNBSE)Class 8 Science★ 4-7 marks in the TN Class 8 annual exam through book-back MCQs, fill-ups and short answers

Matter Around Us

Samacheer Kalvi (TN State Board) Class 8 Science — Chemistry Chapter 9, Matter Around Us. Elements, compounds and mixtures, metals, non-metals and metalloids, the physical properties of metals (malleability, ductility, conductivity), mercury the liquid metal, and symbols of elements. Notes with the actual book-back questions, common mistakes and quick revision.

⏱ 16 min readEasy difficulty✓ Free · NCERT-aligned

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By the end of this chapter you'll be able to…

1Distinguish elements, compounds and mixtures
2Classify elements as metals, non-metals, metalloids
3State the physical properties of metals
4Identify mercury as the liquid metal (Hg)
5Write symbols of common elements

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Why this chapter matters

Matter Around Us classifies substances into elements, compounds and mixtures and teaches the properties of metals (malleability, ductility, conductivity). These — including mercury (Hg) — are directly tested book-back content in the TN Class 8 exam.

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A 5-minute refresher here will save you 30 minutes of confusion below.

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Class 7 — Matter

Solids, liquids and gases.

Matter Around Us — Class 8 Science (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 8 Science, Chemistry — Chapter 9. What everything is made of, and the properties of metals.

1. About this chapter

This chapter covers elements, compounds and mixtures, metals, non-metals and metalloids, the properties of metals, and the symbols of elements.

2. Elements, compounds and mixtures

Element: made of one kind of atom (oxygen, iron). Compound: two or more elements chemically combined in a fixed ratio (water H₂O). Mixture: substances physically mixed (air, salt water), separable by physical methods.
Elements are of three kinds — metals, non-metals and metalloids (metalloids like silicon show properties of both).

3. Properties of metals and non-metals

Metals are usually: malleable (can be hammered into sheets), ductile (drawn into wires), good conductors of heat and electricity, lustrous and sonorous.
Mercury is the only metal that is liquid at room temperature — it is used in thermometers; its symbol is Hg.
Non-metals are generally brittle, poor conductors and dull (e.g., sulphur, carbon).

4. Symbols of elements

Each element has a symbol (one or two letters; first letter capital): H (hydrogen), O (oxygen), Na (sodium), Fe (iron), Hg (mercury), Cl (chlorine).

5. Worked examples

Example 1. Name the liquid metal used in thermometers and give its symbol. Mercury; symbol Hg.

Example 2. What is malleability? The property of metals that lets them be hammered into thin sheets.

Example 3. Differentiate a compound and a mixture. A compound is chemically combined in a fixed ratio (water); a mixture is physically mixed and separable (salt water).

6. Book-back questions (Samacheer Kalvi)

I. Choose the correct answer

The liquid metal used in thermometers is — (a) water / (b) mercury / (c) iron. Ans: (b) mercury.
The symbol of mercury is — (a) Me / (b) Hg / (c) Mr. Ans: (b) Hg.
The property which allows metals to be hammered into sheets is — (a) ductility / (b) malleability. Ans: (b) malleability.

II. Fill in the blanks 4. Metals that can be drawn into wires show the property of ductility. 5. A substance made of only one kind of atom is an element. 6. Air is a mixture of gases.

III. Answer briefly 7. Differentiate metals and non-metals (any two points). 8. Give two examples each of an element, a compound and a mixture.

7. Common mistakes

Mistake: Confusing malleability and ductility. Fix: Malleability = hammered into sheets; ductility = drawn into wires.
Mistake: Calling air a compound. Fix: Air is a mixture of gases.
Mistake: Writing the mercury symbol as Me. Fix: The symbol of mercury is Hg.

8. Quick revision

Chemistry Ch 9 · elements, compounds, mixtures, metal properties.
Element (one atom type), compound (chemically combined), mixture (physically mixed).
Metals: malleable (sheets), ductile (wires), good conductors, lustrous, sonorous.
Mercury = only liquid metal (symbol Hg).
Symbols: first letter capital (Na, Fe, Hg, Cl).

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Element / compound / mixture

one atom type / chemically combined / physically mixed

Compounds have fixed ratios.

Metal properties

malleable, ductile, conductors, lustrous, sonorous

Malleable = sheets; ductile = wires.

Mercury

only liquid metal; symbol Hg

Used in thermometers.

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Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT

✗ Confusing malleability and ductility

✓ Malleability = hammered into sheets; ductility = drawn into wires.

WATCH OUT

✗ Calling air a compound

✓ Air is a mixture of gases.

WATCH OUT

✗ Writing the mercury symbol as Me

✓ The symbol of mercury is Hg.

NCERT exercises (with solutions)

Every NCERT exercise from this chapter — what it covers and how many questions to expect.

Choose the correct answer

Book-back MCQs on mercury, its symbol and malleability.

Questions

Fill in the blanks

Ductility, element and mixture.

Questions

Answer briefly / Match the following

Metals vs non-metals; element/compound/mixture examples.

Questions

Practice problems

Try each one yourself before tapping "Show solution". Active recall > rereading.

Q1EASY· MCQ

The liquid metal used in thermometers is ____.

▶ Show solution

mercury.

Q2EASY· MCQ

The symbol of mercury is ____.

▶ Show solution

Hg.

Q3EASY· MCQ

The property which allows metals to be hammered into sheets is ____.

▶ Show solution

malleability.

Q4EASY· Fill in the blanks

Metals that can be drawn into wires show the property of ____.

▶ Show solution

ductility.

Q5EASY· Answer briefly

Differentiate metals and non-metals (any two points).

▶ Show solution

Metals are malleable, ductile and good conductors and are lustrous; non-metals are generally brittle, poor conductors and dull.

Q6EASY· Concept

Give two examples each of an element, a compound and a mixture.

▶ Show solution

Elements: iron, oxygen; compounds: water, common salt; mixtures: air, salt water.

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

•Chemistry Chapter 9 of Samacheer Kalvi Class 8 Science.
•Element (one atom type), compound (chemically combined), mixture (physically mixed).
•Metals: malleable (sheets), ductile (wires), good conductors, lustrous, sonorous.
•Mercury = only liquid metal (symbol Hg), used in thermometers.
•Non-metals are brittle, poor conductors, dull.
•Symbols: first letter capital (Na, Fe, Hg, Cl).

Tamil Nadu (TNBSE) marks blueprint

Where the marks come from in this chapter — so you can plan your prep.

Typical chapter weightage: 4-7 marks across book-back MCQ, fill-ups and short answers

Question type	Marks each	Typical count	What it tests
MCQ / Fill	1	3-4	Mercury, symbols, metal properties
Short Answer	2-3	1-2	Metals vs non-metals, classification
Match	1-2	0-1	Element/compound/mixture

Prep strategy

Separate malleability and ductility
Remember mercury = liquid metal (Hg)
Classify substances with examples
Memorise common element symbols

Where this shows up in the real world

This chapter isn't just an exam topic — it lives in the world around you.

Materials selection

Metal properties decide their use in wires, sheets and tools.

Thermometers

Mercury's liquid metal property is used to measure temperature.

Separation

Knowing mixtures lets us purify water, salt and metals.

Exam strategy

Battle-tested tips from teachers and toppers for this chapter.

Distinguish malleability and ductility
State mercury's symbol (Hg)
Classify with clear examples
List metal properties precisely

Going beyond the textbook

For olympiad aspirants and curious learners — topics that build on this chapter.

List five metals and the property that makes each useful.
Explain why alloys are mixtures, not compounds.

Where else this chapter is tested

CBSE board isn't the only one — other exams test this chapter too.

TN Class 8 Annual ExamHigh

Foundation / NMMS ScienceMedium

School unit testsHigh

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Questions students ask

The real ones — pulled from the Q&A community and tutor sessions.

Mercury is the only metal that is liquid at room temperature, expands uniformly on heating and is easily visible, making it suitable for thermometers.

An element that shows properties of both metals and non-metals, such as silicon.

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