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CHEMISTRY FORM 2
1. STRUCTURE OF THE ATOM, AND THE PERIODIC TABLE
- 1.1 Structure of the atom
- 1.2 Atomic Number and Mass Number
- 1.3 Isotopes
- 1.4 Energy levels and electron arrangement
- 1.5 Development of the Periodic Table
- 1.6 Relative Atomic Mass and Isotopes
- 1.7 Ion Formation
- 1.8 Chemical Formulae
- 1.9 Chemical Equations
2. CHEMICAL FAMILIES AND PATTERNS IN PROPERTIES
- 2.1 Alkali metals (Group I elements)
- 2.2 Alkali Earth Metals (Group II elements)
- 2.3 Halogens (Group VII elements)
- 2.4 Noble gases (Group VIII elements)
- 2.5 Properties and Trends Across the Periodic Table
3. CHEMICAL BONDING AND STRUCTURE
- 3.1 Bond
- 3.2 Ionic bond
- 3.3 Giant ionic structure
- 3.4 Covalent bond
- 3.5 Co-ordinate bond
- 3.6 Molecular structures
- 3.7 Giant covalent structures
- 3.8 Metallic Bond
- 3.9 Types of bond across a period
- 3.10 Oxides of elements in Period 3
- 3.11 Chlorides of Period 3 elements
4. SALTS
- 4.1 What is a salt?
- 4.2 Types of salt
- 4.3 Solubility of salts in water
- 4.4 Methods of preparing salts
- 4.4.1 Reacting a Metal with an Acid
- 4.4.2 Reacting an Acid with a Base (Neutralization)
- 4.4.3 Reacting an Acid with a Carbonate (or hydrogencarbonate of metal)
- 4.4.4 Combining elements Directly (Direct Combination of elements)
- 4.4.5 Precipitation (Double decomposition)
- 4.5 Action of heat on salts
- 4.6 Uses of salts
5. EFFECT OF AN ELECTRIC CURRENT ON SUBSTANCES
- 5.1 Electrical conduction
- 5.2 Electrical conductivity of molten substances
- 5.3 Electrical conductivity of substances in aqueous state
- 5.4 Electrolysis
- 5.5 Applications of electrolysis
6. CARBON AND SOME OF ITS COMPOUNDS
- 6.1 Allotropes of carbon
- 6.2 Chemical properties of carbon
- 6.3 Carbon (IV) oxide
- 6.4 Carbon (II) oxide (CO)
- 6.5 Large scale production of sodium carbonate and sodium hydrogencarbonate
- 6.6 Effect of carbon (II) oxide and carbon (IV) oxide on the environment
- 6.7 Carbon cycle
Content developer
Effect of an electric current on substances: Electrical conductivity of molten substances
5.0 Effect of an electric current on substances
5.2 Electrical conductivity of molten substances
Observe conduction of electricity by molten lead (II) bromide (PbBr2).
(courtesy Youtube-The electrolysis of lead bromide by David Read)
Questions 5.2
- What type of bond exists between lead and bromine in solid lead (II) bromide?
- What is the structure of lead (II) bromide? Explain.
- Write the formulae of lead (II) ions and bromide ions, indicating their state symbols when molten.
- Which ions move to the anode and which ones move to the cathode?
- Explain why lead (II) bromide conducts electricity in molten state but not in solid state.
- Which of the following substances are also expected to conduct electricity in molten state but not as solids: H2O, NaCl, CS2, CuO, NH3, SiO2, Al2O3, PbI2?
Answers to Questions 5.2
Ionic compounds conduct electricity in molten state because the ionic bonds are broken, setting the ions free to move about. We say the ions are dissociated. In solid state, the ions are held together by strong ionic bonds; so they are not free to move about and conduct electricity. We can use this fact to identify ionic compounds.