CHEMISTRY FORM 2
- 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
- 2.1 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
- 3.1 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
- 4.1 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
- 5.1 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
- 6.1 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
Structure of the Atom, and the Periodic Table: Noble gases (Group VIII elements)
1.0 Structure of the Atom, and the Periodic Table
2.4 Noble gases (Group VIII elements)
Noble gases include helium (He), neon (Ne), argon (Ar), xenon (Xe), and krypton (Kr). Being in Group VIII, their outermost (and inner) energy levels are completely filled with electrons so they are chemically stable (Figure 2.4.1).
Figure 2.4.1: Noble gas atomic structures
Atomic radii of nobe gases increase down the group due to an increase in number of energy levels.
Table 2.4 Atomic radii and melting points of noble gases
|Element||Atomic radius (nm)||Melting point (oC)|
- Noble gases exist as single atoms (mono-atomic molecules). Explain this.
- Although stable and unreactive, some noble gases can be made to react under extreme conditions, such as high temperatures. Which of the elements would be the most difficult to be made to react? Explain your answer.
Answers to Questions 2.4
Noble gases are used in many areas such as in diving and mountaineering gas cylinders, welding, light emitting diodes (LED) and advertisement sign lamps (Figure 2.4.2) because of their rich colored lights.
Figure 2.4.2 Uses of noble gases (courtesy AudioAfricionado.org)
Summary about noble gases
- Noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe)
- They are all gases.
- Their atomic radii increase down the group because of increasing number of energy levels.
- They are unreactive.