KEY NOTES 1-Class 10 – Science -Chemistry -Chapter 3 – Metals and Non-metals

KEY NOTES 1-Class 10 – Science -Chemistry -Chapter 3 – Metals and Non-metals  

Introduction:

·       Metals and non-metals are two broad categories of elements in the periodic table with distinct properties and behaviours.

·       Metals are a class of elements characterized by specific physical and chemical properties.

·       Metals are a class of elements which form positive ions by losing electrons. They are electropositive elements because they can form positive ions by losing electrons

·       Metals: Iron, Zinc, Copper, Aluminium etc.

·       Non – Metals are elements which form negative ions by gaining electrons. They are known as electronegative elements because they can form negative ions by gaining electrons.

·       Non – metals: Chlorine, Nitrogen, Hydrogen, Oxygen, Sulphur etc.

·       Apart from metals and non-metals some elements show properties of both metals and non – metals, e.g. Silicon, Arsenic, Germanium. They are called metalloids

Physical Properties of Metals

Luster: Metals generally have a shiny or metallic luster. This characteristic is due to the ability of metals to reflect light.

Malleability: Metals can be hammered or rolled into thin sheets without breaking. This property is known as malleability.

Ductility: Metals can be drawn into thin wires without breaking. This property is known as ductility.

Conductivity: Metals are excellent conductors of heat and electricity. The presence of free electrons in the metal lattice allows for efficient transmission of heat and electric current.

High Melting and Boiling Points: Metals typically have high melting and boiling points. This contributes to their stability in solid form and their usefulness in various industrial applications.

Solid State (at Room Temperature): Most metals exist in a solid state at room temperature. Mercury is an exception, which remains in a liquid state.

Density: Metals generally have high densities, meaning they have a significant mass packed into a given volume.

Sonorous: Metals produce a ringing sound when struck. This property is known as sonorousness.

Magnetic Properties: Some metals, such as iron, nickel, and cobalt, exhibit magnetic properties.

Reaction with Acids: Metals react with acids to produce hydrogen gas and a salt. The reactivity with acids is a common chemical property of metals.

Chemical Properties of Metals:

Reaction with Oxygen: Metals react with oxygen to form metal oxides. This process is known as oxidation.

4Mg + O₂ à 2Mg₂ O

Reaction with Water: Some metals react with water to form metal hydroxides and hydrogen gas.

Metal + water à Metal oxide + Hydrogen

Metal Oxide + water à Metal hydroxide

2Al +3H₂ O à Al₂ O₃ + 3 H₂

Reaction with Acids: Metals react with acids to produce salts and hydrogen gas.​

Zn+2HCl à ZnCl₂ + H₂  

Examples:

Iron (Fe), Copper (Cu), Aluminium (Al), Gold (Au), and Silver (Ag).

Reaction of metal with salt solution

 Metals react with acids to produce salts and hydrogen gas.

When a more reactive metal is put in salt solution of a less reactive metal, then more reactive metal displaces less reactive metal from its salt solution.

Uses of Metals

Used in construction (iron, aluminum).

Electrical wiring (copper).

Currency (copper, nickel).

Jewelry (gold, silver).