Comprehensive Study Notes on Metals and Non-Metals

Introduction to the Elements

Everything in the environment is composed of different elements, with a total of $118$ elements identified.
These elements are classified into three primary categories based on their properties:
- Metals: Generally hard, lustrous, malleable, and ductile elements with high thermal and electrical conductivity.
- Non-metals: Elements that are brittle, non-lustrous, and poor conductors of heat and electricity.
- Semi-metals or Metalloids: Elements that possess properties common to both metals and non-metals.

Physical Properties of Metals

Metallic Lustre:
- In their pure state, most metals have a shining surface. For example, gold appears shining yellow, copper is brown, while iron, aluminium, and zinc are lustrous grey.
- Mechanism: When light hits a metal surface, atoms absorb photons as energy. This causes atoms to get excited and electrons to vibrate. These vibrating electrons release energy in the form of light, creating a shine.
Hardness:
- The hardness varies between different metals. Hardness is determined by the strength of the metallic bonds within the element.
- Chromium is the hardest metal, while Cesium is the softest metal.
- Alkali metals like Sodium and Potassium are exceptionally soft and can be cut using a knife.
Malleability:
- This is the property that allows metals to be beaten with a hammer into very thin sheets without breaking.
- Gold and silver are recognized as the most malleable metals. Aluminium and copper are also highly malleable.
Ductility:
- Ductility is the ability of a metal to be drawn or stretched into thin wires.
- Gold and silver are the most ductile. For example, a single $100\,mg$ sample of silver can be drawn into a thin wire approximately $200\,metres$ in length.
- Copper and aluminium are very ductile and are predominantly used for electrical wiring.
Thermal Conductivity:
- Metals allow the flow of heat through them via the process of conduction.
- When heated, metal atoms gain energy and vibrate, transferring this energy to neighboring atoms.
- Silver is the best conductor of heat.
- Lead is the poorest conductor of heat among metals. Mercury is also a poor conductor.
Electrical Conductivity:
- Metals facilitate the flow of electric current because they contain free or mobile electrons.
- Silver is the best electrical conductor. Because silver is expensive, copper and aluminium are the standard choices for electric wires.
- Tungsten is a metal that acts as a poor conductor of electricity.
Sonority:
- Sonority (or sonorisity) is the property of producing a ringing or musical sound when struck against a hard object.
- Metals like copper, silver, gold, and aluminium are sonorous.
Melting and Boiling Points:
- Metals generally have high melting points ( $M.P.$ ) and boiling points ( $B.P.$ ) due to the strong attractive forces between metal ions and delocalised electrons.
- Tungsten has the highest melting point among metals.
- Mercury has a notably low melting point.

Allotropes of Carbon and Their Properties

Carbon exists in different forms called allotropes, which exhibit vastly different physical properties:
- Graphite:
  - The structure consists of hexagonal rings where each carbon atom is bonded to three other carbon atoms.
  - Unlike most non-metals, it is a good conductor of electricity.
  - It has an exceptionally high melting point of $3730\,^{\circ}C$ .
- Diamond:
  - Carbon atoms are arranged in a tetrahedral structure where one carbon atom is bonded to four others.
  - The carbon-carbon bond length is often measured at $154\,pm$ .
  - It is the hardest known natural substance and is non-malleable and non-ductile.

Physical Properties of Non-Metals

Physical State:
- Non-metals exist in three states.
- Gases ( $11$ total): Hydrogen ( $H$ ), Nitrogen ( $N$ ), Oxygen ( $O$ ), Fluorine ( $F$ ), Neon ( $Ne$ ), Chlorine ( $Cl$ ), Argon ( $Ar$ ), Krypton ( $Kr$ ), Xenon ( $Xe$ ), Radon ( $Rn$ ), and Helium ( $He$ ).
- Liquid: Bromine ( $Br$ ).
- Solids: Sulphur, Phosphorus, and Diamond.
Lustre:
- Generally non-lustrous and cannot be polished.
- Exceptions: Graphite and Iodine possess metallic lustre.
Mechanical Integrity:
- Non-metals are brittle; they break into small pieces rather than being hammered into sheets or drawn into wires.
- They have low tensile strength and are easily broken.
Density and Conduction:
- Generally light with low densities.
- Usually bad conductors of heat and electricity due to the absence of mobile electrons (Graphite being the exception).
Sonority:
- Non-metals are not sonorous and do not produce a ringing sound.

Comprehensive Distinction Between Metals and Non-Metals

State: Metals are typically solids at room temperature (except Mercury, which is liquid). Non-metals exist in solid, liquid, and gas phases.
Lustre: Metals are lustrous. Non-metals (except iodine and graphite) are not.
Malleability/Ductility: Metals are malleable and ductile (except alkali metals). Non-metals are neither.
Hardness: Metals are generally hard (except alkali metals). Non-metals vary in hardness (Diamond is the hardest substance).
Density: Metals have high densities; non-metals have low densities.
Conductivity: Metals are good conductors. Non-metals are poor conductors (except graphite).
$M.P.$ and $B.P.$ : Metals have high points. Non-metals usually have low points (except Boron, Carbon, and Silicon).

Practical Applications

Metals:
- Used in the construction of buildings and bridges.
- Used for minting coins and manufacturing machine parts or automobiles.
- Used to create kitchen utensils and jewelry.
Non-Metals:
- Oxygen: Essential for respiration in living organisms.
- Nitrogen: Primary constituent of fertilizers.
- Sulphur: Used as a fungicide and in the production of gunpowder.
- Carbon (Graphite): Used as electrodes in dry cells and electrolytic cells.
- Chemical components of food include carbon, hydrogen, oxygen, nitrogen, and sulphur.

Nature of Oxides

Metal Oxides:
- Generally basic in nature. For example, burning magnesium produces ashes that, when dissolved in water, turn red litmus blue.
- Examples: $MgO$ , $Na_2O$ , $K_2O$ , $CaO$ .
- Reaction: $Metal Oxide + Water \rightarrow Metal Hydroxide$
- Equation example: $CaO + H_2O \rightarrow Ca(OH)_2$
Non-Metal Oxides:
- Generally acidic in nature. Dissolved gases from burning sulphur turn blue litmus red.
- Examples: $CO_2$ , $SO_2$ , $SO_3$ , $P_2O_5$ , $NO_2$ , $N_2O_5$ .
- Equation example: $SO_3 + H_2O \rightarrow H_2SO_4$
- Neutral Oxides: Some non-metal oxides are neutral, such as $CO$ , $H_2O$ , and $N_2O$ .
Amphoteric Oxides:
- Oxides of Aluminium ( $Al_2O_3$ ) and Zinc ( $ZnO$ ) behave as both acids and bases.
- They react with both acids and bases to form salt and water.
- Basic metallic oxide reacting with acid: $CuO(s) + H_2SO_4(l) \rightarrow CuSO_4(aq) + H_2O(l)$

Chemical Properties of Metals

Electropositivity:
- Metals tend to lose one or more valence electrons to form positive ions: $M \rightarrow M^{n+} + ne^-$ .
- Chemical reactivity is directly linked to this electron-releasing tendency.
Reaction with Oxygen ( $Metal + Oxygen \rightarrow Metal Oxide$ ):
- Vigorous Reactivity: Sodium ( $Na$ ) and Potassium ( $K$ ) react violently with oxygen and catch fire in moist air. To prevent this, they are stored under kerosene.
- Flame Colours: Sodium burns with a golden yellow flame; Potassium burns with a lilac flame.
- Protective Layers: Metals like $Mg$ , $Al$ , $Zn$ , and $Pb$ react with oxygen to form a protective oxide layer that prevents further oxidation.
- Impact of Heat: Magnesium does not react at room temperature but combines on heating to form magnesium oxide and magnesium nitride. Iron filings burn vigorously when sprinkled in a flame, forming $Fe_3O_4$ .
- Noble Metals: Gold ( $Au$ ) and Silver ( $Ag$ ) do not react with oxygen even at high temperatures.
- Reactivity Order toward Oxygen: $K > Na > Mg > Al > Cu$