Metals and Non-metals

Summary

• Elements are classified as metals or non-metals based on their properties.
• Metals have high melting points, are lustrous, malleable, ductile, and good conductors of heat and electricity.
• Non-metals are generally poor conductors and can be solids, liquids, or gases.
• Metals can form positive ions by losing electrons, while non-metals typically gain electrons.
• Ionic compounds are formed through the transfer of electrons from metals to non-metals.
• The earth's crust is the primary source of metals, found in minerals and ores.
• Metals can undergo displacement reactions based on their reactivity.

Physical Properties of Metals

• Lustre: Metals have a shiny appearance.
• Malleability: Metals can be hammered into thin sheets.
• Ductility: Metals can be drawn into wires.
• Conductivity: Metals conduct electricity and heat well.
• Sonority: Metals produce sound when struck.

Physical Properties of Non-metals

• Non-metals are generally dull, brittle, and poor conductors of heat and electricity (except graphite).
• Most non-metals exist as gases or solids, with bromine being a liquid.

Chemical Properties of Metals

• Metals react with oxygen to form basic oxides.
• Metals can displace hydrogen from dilute acids.
• Reactivity series: Metals are arranged based on their reactivity, with potassium being the most reactive and gold the least.

Ionic Compounds

• Formed by the transfer of electrons from metals to non-metals.
• Properties include:
  • High melting and boiling points.
  • Soluble in water but insoluble in organic solvents.
  • Conduct electricity in molten state or when dissolved in water.

Extraction of Metals

• Metals are extracted from ores, which are minerals with a high concentration of a particular metal.
• The extraction process depends on the metal's reactivity.

Common Mistakes and Exam Tips

• Mistake: Confusing the properties of metals and non-metals.
  • Tip: Remember that metals are generally shiny and conductive, while non-metals are dull and insulative.
• Mistake: Misunderstanding the reactivity series.
  • Tip: Familiarize yourself with the order of metals in the reactivity series for displacement reactions.

Metals and Non-metals

3.1 Physical Properties

3.1.1 Metals

• Metallic Lustre: Metals have a shining surface in their pure state.
• Hardness: Varies among metals; some can be cut with a knife (e.g., sodium).
• Malleability: Metals can be hammered into thin sheets.
• Ductility: Metals can be drawn into wires.
• Conductivity: Metals are good conductors of electricity and heat.
• Sonority: Metals produce sound when struck.

Activities to Observe Metal Properties

1. Activity 3.1: Clean and observe samples of iron, copper, aluminium, and magnesium.
2. Activity 3.2: Cut metals with a knife and observe.
3. Activity 3.6: Set up an electric circuit to test conductivity of metals.

3.1.2 Non-metals

• Non-metals are fewer in number compared to metals.
• Examples: Carbon, sulphur, iodine, oxygen, hydrogen.
• Physical states: Mostly solids or gases, except bromine (liquid).

Activities to Observe Non-metal Properties

1. Activity 3.7: Collect samples of carbon, sulphur, and iodine; perform similar tests as for metals.

3.2 Chemical Properties of Metals

• Metals react with water and acids, forming basic oxides.
• Most non-metals produce acidic oxides when dissolved in water.

Example Reactions

• Magnesium + Sulphur: Produces a basic solution.
• Burning Sulphur: Produces acidic fumes.

3.3 Reactivity of Metals and Non-metals

• Reactivity is related to the tendency to achieve a stable electron configuration.
• Metals lose electrons to form positive ions; non-metals gain electrons to form negative ions.

Summary of Key Points

• Metals are generally lustrous, malleable, ductile, and good conductors.
• Non-metals have properties opposite to metals; they are not malleable or ductile and are poor conductors, except for graphite.
• The extraction of metals involves processes like electrolysis and reduction.
• Corrosion is a common issue with metals like iron when exposed to moisture.

Common Mistakes and Exam Tips

Common Pitfalls

• Misclassification of Elements: Students often classify elements incorrectly based on physical properties alone, overlooking exceptions such as iodine being lustrous (a non-metal) and gallium having a low melting point (a metal).
• Ignoring Chemical Properties: Failing to consider chemical properties when classifying metals and non-metals can lead to misunderstandings, as many metals and non-metals behave differently in reactions.
• Overlooking Exceptions: Students may forget that not all metals are solid at room temperature (e.g., mercury) and that some non-metals can exist in different forms (allotropes).

Tips for Success

• Understand Properties: Familiarize yourself with the physical and chemical properties of metals and non-metals, including malleability, ductility, and conductivity.
• Conduct Experiments: Engage in hands-on activities to observe properties directly, such as testing conductivity and observing reactions with acids.
• Use Tables: Create comparison tables for metals and non-metals to visualize differences in properties and reactivity.
• Practice Reactions: Write out and balance chemical equations for reactions involving metals and non-metals to reinforce understanding.
• Review the Activity Series: Memorize the activity series of metals to predict reactivity and displacement reactions effectively.