Metal and Non-Metal

Unit: 17

Book Icon Class 9: science

Introduction to Metal, General Properties of Metal, Difference between metal and non-metal, Important metals for Human Body, Harmful effect of Mercury and Lead

Introduction to Metal

Metals are a class of elements characterized by their ability to conduct electricity and heat, malleability, ductility, and a shiny appearance. Most metals are solid at room temperature, except mercury. They are widely used in construction, manufacturing, and technology due to their strength, conductivity, and versatility.

General Properties of Metals

The physical and chemical properties of metals are given below.

A. Physical Properties of Metals

1. Luster: Metals have a shiny appearance when polished.

2. Conductivity: Good conductors of heat and electricity.

3. Malleability: Can be hammered or rolled into thin sheets.

4. Ductility: Can be drawn into wires.

5. High Density: Generally have high density and are heavy.

6. Sonorous: Produce a ringing sound when struck.

7. High Melting and Boiling Points: Most metals have high melting and boiling points.

B. Chemical Properties of Metals

1. When metals are heated with oxygen, they form corresponding metal oxides. The metal oxides are basic in nature.

\(\begin{aligned} & \text{Reactions:} \\ & \text{Metal} + \text{Oxygen} \rightarrow Metal oxide \\ & \text{1. } Na + O_2 \rightarrow Na_2O \\ & \text{2. } Mg + O_2 \rightarrow MgO \\ & \text{3. } Cu + O_2 \rightarrow CuO \end{aligned}\)

2. Active metals react with dilute acid and form metal salt and Hydrogen gas.

\(\begin{aligned} & \text{Reactions:} \\ & \text{Active metal} + \text{dil. acid} \rightarrow \text{Metal salt} + \text{Hydrogen gas} \\ & \text{1. } Mg + \text{dil.} HCl \rightarrow MgCl_2 + H_2 \\ & \text{2. } Zn + \text{dil.} HCl \rightarrow ZnCl_2 + H_2 \\ & \text{3. } Fe + \text{dil.} HCl \rightarrow FeCl_3 + H_2 \end{aligned}\)

3. Active metals like Lithium, Sodium, Calcium etc. react with water and form metal hydroxide (Alkali) and Hydrogen gas.

\(\begin{aligned} & \text{Reactions:} \\ & \text{Active Metal} + \text{Water} \rightarrow \text{Metal hydroxide} + \text{Hydrogen gas} \\ & \text{1. } Li + H_2O \rightarrow LiOH + H_2\\ & \text{2. } Na + H_2O \rightarrow NaOH + H_2 \\ & \text{3. } Ca + H_2O \rightarrow Ca(OH)_2 + H_2 \end{aligned}\)

Difference Between Metals and Non-Metals

The differences between metals and non-metals are discussed thoroughly in following table.

Property	Metals	Non-metals
Luster	Shiny	Dull (except iodine)
Conductivity	Good conductors of heat and electricity	Poor conductors
Malleability	Malleable	Brittle
Ductility	Ductile	Not ductile
Density	High	Low
Melting/Boiling Points	High	Generally Low
State	Mostly solid (Except Mercury)	Solid, liquid, or gas

Important Metals for the Human Body

1. Iron (Fe): Vital for hemoglobin, which transports oxygen in the blood.

2. Calcium (Ca): Essential for strong bones and teeth, and plays a role in muscle contractions.

3. Magnesium (Mg): Regulates nerve and muscle functions and maintains a healthy immune system.

4. Zinc (Zn): Supports the immune system and aids in cell growth.

5. Potassium (K): Helps maintain proper nerve and muscle function.

Harmful Effects of Mercury and Lead

The harmful effects of Mercury and Lead are discussed below.

1. Mercury

- Toxic to the nervous system, kidneys, and lungs.

- Can cause memory loss, mood swings, and tremors.

- Exposure through fish consumption or industrial pollution can lead to mercury poisoning.

2. Lead

- Affects brain development in children, causing cognitive and behavioral issues.

- Can damage the nervous system, kidneys, and cardiovascular system.

- Found in old paints, contaminated water, and industrial waste.

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