Comprehensive Study Notes on Metals and Non-Metals

Elements and Atoms

• Definition of an Element: A substance that cannot be broken down into two or more simpler substances by chemical reactions (such as by applying heat, light, or electricity).
• Simplest Form: Elements themselves are the simplest substances, which is why they cannot be split up or broken down further.
  • Example: Iron is an element because it cannot be broken down into simpler substances by usual chemical reaction methods like heat, light, or electricity.
• Common Elements: Hydrogen, Helium, Carbon, Nitrogen, Oxygen, Sulphur, Phosphorus, Silicon, Chlorine, Bromine, Iodine, Sodium, Potassium, Magnesium, Calcium, Aluminium, Iron, Zinc, Copper, Silver, Gold, and Mercury.
• Chemical Symbols:
  • Every element is represented by a unique symbol; no two elements share the same symbol.
  • A symbol is a short way to write an element and also represents one atom of that element.
  • Examples: The symbol for Hydrogen is $\text{H}$, and the symbol for Magnesium is $\text{Mg}$.
• Concept of Atoms:
  • An atom is the smallest particle of an element.
  • A sample of a given element contains only one kind of atom.
  • Second Definition of an Element: An element is a substance made up of only one kind of atom.
  • There are as many types of atoms as there are elements. For instance, sulphur element contains only sulphur atoms, and iron element contains only iron atoms.
  • Atoms of an element remain unaffected by physical changes in the element. An atom of liquid (molten) sulphur or sulphur vapour is identical to an atom of solid sulphur.
• Abundance and Classification:
  • Total known elements today: $118$ elements.
  • Naturally occurring elements: $92$ elements.
  • Elements are broadly classified on the basis of their properties into two main groups: Metals and Non-Metals.

Physical Properties of Metals

• General Characteristics:
  • Metals are malleable and ductile elements that are good conductors of heat and electricity.
  • They are lustrous (shiny), hard, strong, sonorous, heavy (high density), and have high melting and boiling points.
  • State at Room Temperature: All metals are solids except Mercury, which is a liquid metal.
  • Abundance: Out of $92$ naturally occurring elements, $70$ elements are metals.
  • Examples: Iron, Copper, Aluminium, Zinc, Silver, Gold, Platinum, Chromium, Sodium, Potassium, Magnesium, Nickel, Cobalt, Tin, Calcium, Lead, Cadmium, Mercury, Antimony, Tungsten, Manganese, and Uranium.
• Malleability:
  • The property which allows metals to be hammered or beaten into thin sheets without breaking.
  • Gold and silver are the best malleable metals and can be hammered into extremely fine sheets or foils.
  • Aluminium and copper are also highly malleable (e.g., aluminium foil, copper sheets). Iron is malleable and can be hammered into sheets to make tools such as axes, spades, and shovels by an ironsmith.
• Ductility:
  • The property which allows metals to be drawn or stretched into thin wires.
  • Gold and silver are among the most ductile metals. A mass of $1\,g$ of gold can be drawn into a wire $2\,km$ in length.
  • Copper and aluminium are very ductile and used as electric wires.
  • Iron wires are used for making wire gauzes; magnesium wires are used in science laboratory experiments; thin tungsten wires are used for filaments in electric light bulbs.
• Thermal and Electrical Conductivity:
  • Metals allow heat and electricity to pass through them easily.
  • Thermal Conduction: Silver is the best conductor of heat. Copper is a better conductor than aluminium. Cooking utensils (such as frying pans) are made of metal to conduct stove heat quickly to food, while handles are made of plastic or wood to prevent burns.
  • Electrical Conduction: Silver is the best conductor of electricity, followed by copper. Copper wires are used for household electric wiring.
  • Circuit Demonstration: Placing an aluminium foil or iron nail between crocodile clips in an electric circuit allows current to pass, illuminating the circuit torch bulb.
• Lustre:
  • Metals have a shiny appearance known as metallic lustre on their freshly cut surfaces.
  • Gold and silver are used for jewellery and decoration because of their bright and shiny appearance.
• Sonorousness:
  • Metals make a ringing sound when struck with a hard object or dropped on a floor.
  • Used in making bicycle bells, temple bells, and electric bell gongs.
• Hardness:
  • Most metals are hard and cannot be cut easily. Iron is very hard, whereas aluminium is less hard and can be cut with scissors.
  • Exceptions: Sodium and potassium are soft metals that can be cut easily with a knife (like wax). Magnesium can also be cut easily.

Physical Properties of Non-Metals

• General Characteristics:
  • Non-metals are elements that are neither malleable nor ductile; they are brittle.
  • They do not conduct heat and electricity, are not lustrous (dull), are not sonorous, are light (low density), and have low melting and boiling points.
  • State at Room Temperature: Non-metals can exist as solids, liquids, or gases.
  • Abundance: Out of $92$ naturally occurring elements, $22$ elements are non-metals.
  • $10$ non-metals are solids.
  • $1$ non-metal is liquid (Bromine).
  • $11$ non-metals are gases.
  • Examples: Carbon, Sulphur, Phosphorus, Hydrogen, Oxygen, Nitrogen, Fluorine, Chlorine, Bromine, Iodine, Helium, Neon, Argon, Krypton, and Xenon.
• Brittleness (Lack of Malleability and Ductility):
  • Solid non-metals break into small pieces when hammered or stretched.
  • Brittleness: The property due to which solid non-metals break on hammering.
  • Examples: Forms of carbon (charcoal, coke, coal, graphite/pencil lead) and sulphur break into pieces upon hammering or stretching.
• Conductivity Exceptions:
  • Non-metals are generally poor conductors (insulators).
  • Thermal Exception: Diamond (a form of carbon) is a non-metal that is a good conductor of heat.
  • Electrical Exception: Graphite (a form of carbon) is a non-metal that is a good conductor of electricity and is used to make electrodes in dry cells.
  • Note: Non-conducting substances like plastic, wood, silica, asphalt, rubber, oil, and glass are not non-metals because they are not elements.
• Appearance (Lustre):
  • Non-metals are generally dull in appearance (e.g., sulphur and phosphorus).
  • Exception: Iodine is a non-metal with a shiny, lustrous surface like metals.
• Hardness:
  • Most solid non-metals are soft and easily cut with a knife (e.g., sulphur and phosphorus).
  • Exception: Diamond is extremely hard and is the hardest natural substance known.

Comparison of Physical Properties

• Malleability and Ductility:
  • Metals: Malleable and ductile.
  • Non-Metals: Neither malleable nor ductile; brittle.
• Conductivity:
  • Metals: Good conductors of heat and electricity.
  • Non-Metals: Poor conductors of heat and electricity (except graphite, which conducts electricity).
• Lustre:
  • Metals: Lustrous (shiny).
  • Non-Metals: Non-lustrous; dull in appearance (except iodine, which is lustrous).
• Strength and Tensile Strength:
  • Metals: Strong with high tensile strength (except sodium and potassium).
  • Non-Metals: Not strong; low tensile strength.
• Sonorousness:
  • Metals: Sonorous (produce a ringing sound when struck).
  • Non-Metals: Not sonorous.
• Hardness:
  • Metals: Generally hard (except sodium and potassium, which are soft).
  • Non-Metals: Solid non-metals are soft (except diamond, which is extremely hard).

Chemical Properties of Metals

• Reaction with Oxygen:
  • Metals react with oxygen upon burning in air to form metal oxides, which are basic in nature.
  • $\text{Metal} + \text{Oxygen} \rightarrow \text{Metal oxide (Basic oxide)}$
  • Basic metal oxides turn red litmus paper blue.
  • Magnesium Reaction:
  • $\text{Magnesium (Mg)} + \text{Oxygen (O}_2\text{)} \rightarrow \text{Magnesium oxide (MgO)}$
  • $\text{Magnesium oxide (MgO)} + \text{Water (H}_2\text{O)} \rightarrow \text{Magnesium hydroxide [Mg(OH)}_2\text{]}$
  • $\text{Mg(OH)}_2$ turns red litmus paper blue.
  • Sodium Reaction: Sodium burns to form sodium oxide ($\text{Na}_2\text{O}$), which dissolves in water to form a basic solution that turns red litmus blue.
• Rusting of Iron:
  • Iron combines slowly with oxygen and water vapour present in damp air to form iron oxide (rust).
  • $\text{Iron (Fe)} + \text{Oxygen (O}_2\text{)} + \text{Water (H}_2\text{O)} \rightarrow \text{Iron oxide (Fe}_2\text{O}_3\text{) [Rust / Basic oxide]}$
  • Necessary Conditions: (i) Presence of oxygen (air), and (ii) Presence of water or water vapour (moisture).
  • Accelerating Factors: High air humidity (coastal areas) and dissolved salt in water (seawater accelerates rusting compared to fresh water).
• Corrosion of Other Metals:
  • Corrosion Definition: The gradual deterioration of a metal surface when exposed to moist air or chemicals.
  • Silver: Turns black on prolonged atmospheric exposure.
  • Copper: Forms a green coating when exposed to moist air over time due to basic copper carbonate formation.
  • $2\text{Cu} + \text{H}_2\text{O} + \text{CO}_2 + \text{O}_2 \rightarrow \text{CuCO}_3 \cdot \text{Cu(OH)}_2$
• Prevention of Rusting:
  • Rust is soft and porous, continuously flaking off and eating away iron structure.
  • Painting: Blocks air and moisture from contacting iron surfaces (used on window grills, railings, steel furniture, bridges, railway coaches, car/bus bodies).
  • Greasing / Oiling: Protects machine parts and iron tools from air and moisture.
  • Galvanisation: Depositing a thin coating of zinc metal on iron objects by dipping them in molten zinc. Used for buckets, drums, dustbins, roof sheds, and water pipes.
• Ancient Indian Metallurgy Case Study:
  • The Iron Pillar near Qutub Minar in Delhi is over $7\,m$ high, weighs over $6000\,kg$, and was built over $1600$ years ago during the reign of Chandragupta II (Gupta dynasty). It has not rusted despite long exposure, showcasing historical technological advancement in rust resistance.
• Reaction with Water:
  • $\text{Metal} + \text{Water} \rightarrow \text{Metal hydroxide} + \text{Hydrogen gas}$
  • Reactivity variations:
  • Violent with cold water: Sodium ($\text{Na}$) and Potassium ($\text{K}$).
  • $\text{Sodium (Na)} + \text{Water (H}_2\text{O)} \rightarrow \text{Sodium hydroxide (NaOH)} + \text{Hydrogen (H}_2\text{)}$
  • Slow with cold water, rapid with boiling water/steam: Magnesium ($\text{Mg}$).
  • Slow with steam: Zinc ($\text{Zn}$) and Iron ($\text{Fe}$).
  • Unreactive with water/steam: Copper ($\text{Cu}$), Silver ($\text{Ag}$), and Gold ($\text{Au}$).
  • Storage of Reactive Metals: Sodium and potassium react explosively with air components and moisture, so they are always stored submerged under kerosene.

Chemical Properties of Non-Metals

• Reaction with Oxygen:
  • Non-metals burn in air to form non-metal oxides, which are acidic in nature.
  • $\text{Non-metal} + \text{Oxygen} \rightarrow \text{Non-metal oxide (Acidic oxide)}$
  • Acidic non-metal oxides turn blue litmus paper red.
  • Sulphur Reaction:
  • $\text{Sulphur (S)} + \text{Oxygen (O}_2\text{)} \rightarrow \text{Sulphur dioxide (SO}_2\text{)}$ (Sulphur dioxide is a poisonous gas).
  • $\text{Sulphur dioxide (SO}_2\text{)} + \text{Water (H}_2\text{O)} \rightarrow \text{Sulphurous acid (H}_2\text{SO}_3\text{)}$
  • $\text{H}_2\text{SO}_3$ turns blue litmus paper red.
  • Carbon Reaction:
  • $\text{Carbon (C)} + \text{Oxygen (O}_2\text{)} \rightarrow \text{Carbon dioxide (CO}_2\text{)}$
  • $\text{Carbon dioxide (CO}_2\text{)} + \text{Water (H}_2\text{O)} \rightarrow \text{Carbonic acid (H}_2\text{CO}_3\text{)}$
  • $\text{H}_2\text{CO}_3$ turns blue litmus paper red.
• Reaction with Water:
  • Non-metals do not react with water or steam.
  • Storage of Reactive Non-Metals: Highly reactive non-metals are stored under water to prevent atmospheric contact. For example, Phosphorus catches fire in air, so it is stored in bottles containing water.

Applications and Uses

• Uses of Metals:
  • Cooking utensils and factory water boilers: Made of iron, copper, and aluminium.
  • Electrical transmission: Copper is used for household wiring, motors, and dynamo armatures. Aluminium is used for thick overhead transmission cables.
  • Packaging: Aluminium foil is used for wrapping food, chocolates, and medicines.
  • Transport and Aviation: Aluminium alloys are used to make aeroplanes. Iron/steel is used for cars, buses, trains, bridges, and railway lines.
  • Construction and Hardware: Iron (steel) is used to make nails, screws, pipes, railings, gas cylinders, tools, and agricultural implements.
  • Rust Protection: Zinc is used for galvanising iron.
  • Jewellery: Silver and gold are used due to high lustre.
  • Instruments: Liquid Mercury is used in thermometers.
  • Biological Function: Iron is present in haemoglobin (red blood cells), transporting oxygen throughout body tissues. Deficiency lowers haemoglobin levels, causing oxygen shortage, tiredness, and weakness.
• Uses of Non-Metals:
  • Structural Biology: Living organisms consist of compounds of non-metals (Carbon, Hydrogen, Oxygen, Nitrogen, Sulphur, Phosphorus).
  • Breathing and Combustion: Oxygen is essential for respiration in plants and animals and for burning fuels.
  • Agriculture and Food Preservation: Nitrogen is used to make fertilisers for plant growth and as an inert gas in food packaging to keep food fresh.
  • Water Purification: Chlorine kills germs to supply germ-free drinking water.
  • Antiseptic: Iodine is used to make tincture iodine (a purple solution) applied on cuts and wounds.
  • Pyrotechnics: Sulphur and phosphorus are used in fireworks/crackers.
  • Rubber Manufacturing: Sulphur is used in the vulcanisation (hardening) of rubber.
  • Fuel: Carbon in the forms of charcoal, coke, and coal is used as fuel.