Metals and Non-metals

Learning Objectives

• Understand the reactivity of metals with oxygen, water, and acids, focusing on the formation and properties of metal oxides, including amphoteric behavior.
• Calculate and predict the formation of ionic compounds through electron transfer, exemplified by sodium chloride and magnesium chloride, and analyze their properties such as high melting points and electrical conductivity.
• Explore metal extraction techniques from ores, including reduction, electrolysis, and refining methods like electrolytic refining, based on the reactivity of metals.
• Analyze displacement reactions to determine metal reactivity and establish the reactivity series of metals.
• Investigate the mechanisms of corrosion in metals, particularly iron, and evaluate methods to prevent it, such as galvanization and alloying.
• Examine how alloying alters metal properties and its applications, with examples like stainless steel and brass.
• Study the physical properties of metals and non-metals, including lustre, malleability, ductility, sonority, conductivity, and hardness, noting exceptions.
• Investigate the reactions of metals with cold water, hot water, steam, and dilute acids, including the evolution of hydrogen gas.
• Analyze the properties of ionic compounds, focusing on hardness, brittleness, melting point, solubility, and electrical conductivity.

Chapter Notes

Metal Reactivity and Oxidation

• Metal Reactivity: Metals react with oxygen to form metal oxides.
  • Example: $2Cu + O_2 \rightarrow 2CuO$ (Copper forms copper(II) oxide)
  • Amphoteric Oxides: Some metal oxides like $Al_2O_3$ and $ZnO$ show both acidic and basic properties.
• Reactivity with Water:
  • Metals like $K$ and $Na$ react vigorously with cold water.
  • $2K + 2H_2O \rightarrow 2KOH + H_2 + \text{heat}$
  • Metals like $Mg$ react with hot water, while $Al$, $Fe$, and $Zn$ react with steam.

Ionic Bonding and Compound Formation

• Ionic Compounds: Formed by electron transfer from metals to non-metals.
  • Example: Sodium chloride ($NaCl$) formation involves $Na$ losing an electron to form $Na^+$ and $Cl$ gaining an electron to form $Cl^-$.
• Properties:
  • High melting and boiling points due to strong ionic bonds.
  • Conduct electricity in molten state or when dissolved in water.

Metal Extraction Techniques

• Low Reactivity Metals: Extracted by heating alone (e.g., $Hg$ from $HgS$).
• Medium Reactivity Metals: Extracted by converting ores to oxides via roasting or calcination, followed by reduction.
  • Example: $2ZnS + 3O_2 \rightarrow 2ZnO + 2SO_2$
• High Reactivity Metals: Extracted by electrolysis (e.g., $Na$, $Mg$).

Displacement Reactions and Reactivity Series

• Reactivity Series: Determines the ability of a metal to displace another from its compound.
  • Example: $\text{Metal A} + \text{Salt of B} \rightarrow \text{Salt of A} + \text{Metal B}$
• Series Order: $K > Na > Ca > Mg > Al > Zn > Fe > Pb > [H] > Cu > Hg > Ag > Au$

Corrosion and Prevention

• Corrosion: Metals like iron form rust ($Fe_2O_3 \cdot xH_2O$) when exposed to moisture and air.
• Prevention Methods:
  • Galvanization (coating with zinc)
  • Alloying (e.g., stainless steel)

Properties and Uses of Alloys

• Alloys: Mixtures of metals or metals with non-metals to enhance properties.
  • Example: Brass (copper and zinc), Bronze (copper and tin)
• Properties: Improved strength, resistance to corrosion, and altered electrical conductivity.

Physical Properties of Metals and Non-metals

• Metals: Lustrous, malleable, ductile, good conductors of heat and electricity.
• Non-metals: Generally brittle, non-conductive, and lack metallic luster.

Reactions of Metals with Water and Acids

• Water Reactions:
  • Vigorous with $K$ and $Na$.
  • Less vigorous with $Ca$ and $Mg$.
• Acid Reactions:
  • Metals react with acids to produce hydrogen gas.
  • $\text{Metal} + \text{Dilute Acid} \rightarrow \text{Salt} + H_2$

Properties of Ionic Compounds

• Characteristics:
  • Hard, brittle solids with high melting points.
  • Soluble in water, conduct electricity in aqueous or molten state.