Chapter 3: Metals and Non-Metals

This chapter explores the differences between metals and non-metals, their properties, and reactions. Below are the comprehensive notes covering each topic holistically.

1. Physical Properties of Metals and Non-Metals

Metals:

• Lustrous (Shiny): Metals in their pure state, have a shining surface . They reflect light when polished.
• Malleability: Most of the metals, when beaten can be converted into thin sheet. like iron and aluminum can be hammered into thin sheets.
• Ductility: Most of the metals have ability to be converted into wire . Metals like copper and gold etc. can be drawn into wires.
• Conductivity: Metals are good conductors of heat and electricity (e.g., copper, aluminium).
• Sonorous: Produce a ringing sound when struck (e.g., bells made of metals).
• Hardness: Metals are generally hard (e.g., iron), except for sodium and potassium, which are soft and mercury which is liquid at room temperature.
• High melting point:- metals have high melting points but gallium and caesium have very low melting points. These two metals will melt if you keep them on your palm
• Hydrogen gas is not evolved when a metal reacts with nitric acid. It is because HNO3 is a strong oxidising agent. It oxidises the H2 produced to water and itself gets reduced to any of the nitrogen oxides (N2 O, NO, NO2 ).

  Non-Metals:

• Non-lustrous: Generally Non-metals are non lustrous, except for iodine.
• Brittle: Non-metals are generally weak, like sulfur break easily when hammered, But Diamond which is an allotrope of carbon is the hardest known natural substance
• Poor Conductors: Non-metals generally do not conduct heat and electricity only exception is graphite . sulfur and phosphorus do not conduct heat and electricity.
• Non-ductile and Non-malleable: Non-metals cannot be drawn into wires or beaten into sheets.
• Out of 22 non metals 10 are solid 11 are gases and 1 is liquid (Bromine).
• Non-metals generally gain electrons to form anions due to their high electronegativity. However, exceptions like hydrogen can lose an electron to form H⁺ Carbon can also lose electrons in specific organic reactions, but such cases are rare.

2. Chemical Properties of Metals

• Reactivity with Oxygen: Metals react with oxygen to form metal oxides. For example: – 4Na + O₂ → 2Na₂O (Sodium oxide)
• 2Mg + O₂ → 2MgO (Magnesium oxide)

Metal oxides are basic in nature, e.g., Na₂O forms NaOH in water.

• Reactivity with Water: Metals like sodium and potassium react vigorously with cold water: – 2Na + 2H₂O → 2NaOH + H₂↑
• Magnesium reacts with hot water.

       while iron reacts with steam: Fe + H₂O → Fe₃O₄ + H₂↑

• Reactivity with Acids:– Metals generally react with all type of acids to Produce respective salt and hydrogen gas: – Zn + 2HCl → ZnCl₂ + H₂↑
• Reactivity with Bases:– Some metals react with bases like sodium hydroxide to form complex compounds: – Zn + 2NaOH → Na₂ZnO₂ + H₂↑ (Sodium zincate)

Aqua regia :- is a highly corrosive mixture of nitric acid (HNO₃) and hydrochloric acid (HCl), usually in a molar ratio of 1:3. It is known for its ability to dissolve noble metals like gold (Au) and platinum (Pt), which are resistant to most other chemicals

3. Chemical Properties of Non-Metals

• Reactivity with Oxygen:- Non-metals form acidic oxides or neutral oxides when reacting with oxygen: – S + O₂ → SO₂ (Sulphur dioxide) which is acidic in nature
• Reactivity with Water and Acids:– Non-metals generally do not react with water or dilute acids. However some non metal oxide react with water and form acid.
• Reactivity with Bases:- Non-metals react with bases to form salts and water.

        Example:- Chlorine reacts with NaOH to form sodium chloride, sodium hypochlorite, and water.   Cl₂ + 2NaOH → NaCl + NaOCl + H₂O

• Reaction with Hydrogen: Non-metals react with hydrogen to form covalent compounds called hydrides.

• Example: Nitrogen reacts with hydrogen to form ammonia (NH₃).

N2​+3H2​→2NH3

• Electronegativity and Reactivity: Non-metals are generally more electronegative, meaning they tend to gain electrons in reactions to form anions (negative ions). This is why they readily form covalent bonds with other non-metals by sharing electrons.

Amphoteric oxides : – Oxides that show basic as well as acidic behaviour are known as Amphoteric oxides .Aluminium Oxide is one of them.

Zinc also forms amphoteric oxides.

4. Ionic and Covalent Bonding

• Ions

Ions are electric charge that atoms or molecules carry due to the loss or gain of one or more electrons. There are two types of ions:

1. Cations: Positively charged ions, formed when an atom loses electrons (e.g., Na⁺).
2. Anions: Negatively charged ions, formed when an atom gains electrons (e.g., Cl⁻).

• Ionic Bond

An ionic bond is a type of chemical bond formed between two atoms when one atom transfers electrons to another. This results in one atom becoming a positively charged ion (cation) and the other a negatively charged ion (anion). The electrostatic attraction between these oppositely charged ions holds them together. Generally reaction between metal and non-metal forms ionic bond /ionic compound. Example: Sodium chloride (NaCl) is formed by the ionic bond between Na⁺ and Cl⁻.

• Covalent Bond

A covalent bond is a chemical bond formed when two atoms share one or more pairs of electrons. Instead of transferring electrons, the atoms achieve stability by sharing them. Covalent bonds usually occur between non-metal atoms. Example: A water molecule (H₂O) is formed by covalent bonds between hydrogen and oxygen atoms.

• Reactivity Series of Metals

The Reactivity Series is a list of metals arranged in order of their reactivity, from the most reactive to the least reactive. It helps in predicting how metals will react with other substances such as water, acids, and other metals.

Key Features:

Highly Reactive Metals: These metals react vigorously with water and acids, and can displace less reactive metals from their compounds.

Less Reactive Metals: These metals do not react easily with water or acids and are often found in their pure form in nature.

Non-reactive Metals: These metals, like gold and platinum, do not corrode or react under normal conditions.

Reactivity Series (List)

1. Potassium (K)
2. Sodium (Na)
3. Calcium (Ca)
4. Magnesium (Mg)
5. Aluminium (Al)
6. Zinc (Zn)
7. Iron (Fe)
8. Lead (Pb)
9. Hydrogen (H)
10. Copper (Cu)
11. Silver (Ag)
12. Gold (Au)
13. Platinum (Pt)

Metals higher in the series are more reactive, while metals lower in the series are less reactive.

5. Occurrence of Metal

Metals occur in nature either in their free state or in the form of compounds, depending on their reactivity.

1. Native (Free) State: – Less reactive metals like gold, silver, and platinum are found in their native form because they do not react easily with other elements. These metals are often found in elemental form, in river beds or deep within the Earth’s crust.
2. Combined State:- More reactive metals like aluminium, iron, and sodium occur in the form of compounds such as oxides, carbonates, sulfides, or chlorides.

These compounds are extracted from ores, which are minerals containing a high concentration of metal.

Examples of Metal Ores:

Iron (Fe): Found in ores like hematite (Fe₂O₃) and magnetite (Fe₃O₄).

Aluminium (Al): Extracted from bauxite (Al₂O₃.2H₂O).

Copper (Cu): Obtained from copper pyrite (CuFeS₂).

Metals are extracted from ores through processes like reduction and electrolysis based on their position in the reactivity series.

Reduction method for less reactive metals (e.g., copper).

Electrolysis method for highly reactive metals (e.g., sodium).

Roasting and smelting method for medium reactive metals

Enrichment of Ores: – Metal enrichment refers to the process of increasing the concentration of a specific metal within an ore to make it more economically viable for extraction.

6. Corrosion of Metals

Corrosion:-  Metals when  Exposed to air and moisture undergo a chemical reaction that is know as corrosion. E.g. iron (fe) when exposed to air and moisture forms rust (Rusting of iron). Equation for rusting:- Fe + O₂ + H₂O → Fe₂O₃.xH₂O (Rust)

Prevention:- Methods include galvanization, painting, and electroplating.

7. Alloys

Alloys:- A mixture of two or more metals or a metal and a non-metal. They are made to enhance properties like strength, resistance to corrosion, etc.

Example: Steel (Iron + Carbon), Brass (Copper + Zinc).

8. Uses of Metals and Non-Metals

Metals:

Iron: Construction and manufacturing of machinery.

Copper: Electrical wiring.

Aluminium: Aircraft bodies and utensils.

Non-Metals:

Oxygen: Essential for respiration.

Carbon: Used in fuels like coal and in the form of diamonds.

Sulfur: Used in making sulfuric acid.