Reaction with Oxygen: Metals react with oxygen to form basic oxides (e.g., ). Some metals like Aluminum form amphoteric oxides, which exhibit both acidic and basic behaviors depending on the reacting medium.
Reaction with Water: Highly reactive metals react with cold water to produce hydroxides and hydrogen gas, while less reactive ones may only react with steam or not at all. This variation is used to rank metals in the Reactivity Series.
Displacement Reactions: A more reactive metal will displace a less reactive metal from its salt solution. This principle is vital for predicting the outcome of chemical reactions and for certain industrial extraction techniques.
Ionic Bond Formation: When a metal reacts with a non-metal, electrons are transferred from the metal to the non-metal. This creates oppositely charged ions that are held together by strong electrostatic forces of attraction.
Properties of Ionic Compounds: Due to the strong lattice structure, these compounds typically have high melting and boiling points. They are generally soluble in water but insoluble in organic solvents like kerosene.
Electrical Conductivity: Ionic compounds do not conduct electricity in the solid state because ions are fixed in position. However, they become excellent conductors when molten or dissolved in water, as the ions become free to move.
Ores and Gangue: Metals are rarely found pure in nature; they exist as ores mixed with impurities called gangue. Metallurgy is the scientific process of extracting pure metal from these ores through various chemical and physical stages.
Enrichment and Reduction: Ores are first concentrated to remove gangue. Low-reactivity metals are often extracted by heating alone, while medium-reactivity metals require reduction with carbon (coke).
Roasting vs. Calcination: Roasting involves heating sulfide ores in the presence of excess air to convert them into oxides. Calcination involves heating carbonate ores in limited air to remove volatile impurities and convert them to oxides.
Electrolytic Refining: Highly reactive metals (like Sodium or Aluminum) are extracted via electrolysis of their molten chlorides or oxides. This method is also used to purify metals, where the impure metal acts as the anode and pure metal as the cathode.
Corrosion Mechanism: Corrosion is the gradual deterioration of metals due to chemical reactions with environmental factors like moisture and oxygen. Rusting of iron is the most common example, requiring both air and water to occur.
Prevention Techniques: Surfaces can be protected through painting, greasing, or galvanization (coating with a thin layer of Zinc). Zinc acts as a sacrificial layer because it is more reactive than iron.
Alloying: An alloy is a homogeneous mixture of two or more metals (or a metal and a non-metal). Alloying changes the properties of the base metal, such as increasing hardness, resistance to corrosion, or lowering the melting point.
Reactivity Series Mastery: Always memorize the order of the reactivity series. It is the 'master key' for solving displacement reaction questions and determining extraction methods.
Amphoteric Oxides: Be prepared to write equations showing an oxide (like ) reacting with both an acid () and a base (). This is a frequent high-mark exam question.
Ionic vs. Covalent: When asked to distinguish between compounds, check the constituent elements. Metal + Non-metal usually indicates ionic bonding with high melting points and conductivity in solution.
Gas Tests: Remember that the reaction of metals with dilute acids produces Hydrogen gas, which is identified by the 'pop' sound test. Ensure you mention both the reagent and the observation in your answers.
