Summary and Exam Tips for Uses of Metals
Uses of Metals is a subtopic of Metals, which falls under the subject Coordinated Science in the Cambridge IGCSE curriculum. Metals are known for their physical properties such as being shiny, dense, malleable, and ductile. They have high melting and boiling points and are excellent conductors of heat and electricity due to delocalised electrons. Chemically, metals form positive ions and their oxides tend to be basic or amphoteric. Metals react with acids to produce hydrogen gas and a salt.
Metallic bonding involves a lattice of positive ions in a sea of delocalised electrons, making metals malleable and good conductors of electricity. Alloys, such as brass, are mixtures of metals with other elements, making them harder than pure metals due to the distortion of atomic layers. Steel is an alloy of iron with elements like chromium and nickel, enhancing properties like corrosion resistance.
Metals react with oxygen, water, and acids differently based on their reactivity. The reactivity series helps predict these reactions, with more reactive metals displacing less reactive ones. Extraction of metals involves processes like reduction with carbon or electrolysis, depending on their position in the reactivity series. For instance, aluminum is extracted from bauxite by electrolysis, while iron is extracted from hematite using carbon. Metals like aluminum and zinc are used in aircraft manufacturing, food containers, and galvanizing due to their unique properties.
Exam Tips
- Remember OIL RIG: Oxidation Is Loss, Reduction Is Gain of electrons. This will help you track electron transfer in reactions.
- Understand Alloys: Know that alloys are mixtures, not compounds, and are harder than pure metals due to distorted atomic layers.
- Reactivity Series: Memorize the reactivity series to predict reactions, especially displacement reactions.
- Rust vs. Corrosion: Use "rust" specifically for iron or steel and "corrosion" for other metals.
- Extraction Methods: Be clear on which metals are extracted by reduction with carbon and which require electrolysis.
