Properties and Reactions of Metals

• Metals exhibit four key properties: luster, conductivity, malleability, and ductility.
• Metals form positive ions (cations) by losing their valence electrons.
• Transition metals are generally harder and denser than other metals; some exhibit magnetic properties.
• Metallic bonding involves a 3D network of cations surrounded by a sea of delocalized electrons.
• Cations are held in place via electrostatic attraction to delocalized electrons, which move freely.
• The metallic bonding model cannot fully explain variations in melting points, hardness, densities, conductivity or magnetism between different metals.
• Reaction between metal and water produces metal hydroxide and hydrogen.
• Reaction between metal and acid produces salt and hydrogen.
• Reaction between metal and oxygen produces metal oxide.
• Delocalized electrons in metals reflect light, causing them to be lustrous.
• Mobile electrons in metals gain kinetic energy when heated, enabling efficient heat conduction.
• Mobile electrons move towards a positive charge in an electrical current, enabling electrical conductivity.
• Metals are malleable and ductile because their non-directional bonds allow layers of cations to slide without disrupting the lattice structure.
• Metals have high densities due to the tight packing of cations in their lattice structure.
• The strong attraction between cations and mobile electrons gives metals high melting points.
• Metals have high tensile strength due to closely packed rows of cations.
• Metallic ores are processed using magnetic and density separation techniques.
• Electrolysis is used to extract metals from minerals.
• Mining metals can clear vegetation, cause erosion, and leave waste, impacting land.
• Mining metals consumes a large amount of water and contaminates waterways with waste runoff.
• Carbon and sulfur oxides released during mining contribute to global warming and acid rain, impacting air quality.
• Habitat loss due to mining activities leads to reduced biodiversity.
• Metals can be recycled by re-melting, re-shaping and re-purposing them without losing essential qualities.
• Recycling metals consumes significantly less energy than mining new materials.

Steps in Metal Recycling

• Collection of scrap metal.
• Preparation: classifying metals as ferrous or non-ferrous, compacting, and shredding.
• Smelting in a secondary smelter designed for recycled metal.
• Purification, chemical treatment, and alloying (mixing with other elements).