physical chemistry lesson notes
physical chemistry lesson notes
Here is the structured layout for this content, perfectly formatted as a ready-to-publish WordPress revision post. Missing electronic configurations for Caesium and Francium have been completed systematically to provide a comprehensive study resource for your students.
Alkali and Alkaline Earth Metals
A. ALKALI METALS
Alkali metals are Group I elements of the periodic table. They are called alkali metals because they react with water to produce highly alkaline solutions. Because they are extremely reactive, they are rarely found free in nature and usually exist combined with other elements.
Atomic and Electronic Properties
The table below lists the various alkali metals in order of their position in the group:
| Alkali Metal | Symbol | Atomic Number | Electronic Configuration |
| Lithium | Li | 3 | 2: 1 |
| Sodium | Na | 11 | 2: 8: 1 |
| Potassium | K | 19 | 2: 8: 8: 1 |
| Rubidium | Rb | 37 | 2: 8: 18: 8: 1 |
| Caesium | Cs | 55 | 2: 8: 18: 18: 8: 1 |
| Francium | Fr | 87 | 2: 8: 18: 32: 18: 8: 1 |
Extraction Method
Alkali metals are extracted through the electrolysis of their molten or fused compounds, which are usually chlorides.
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Example: Sodium is industrially extracted by the electrolysis of molten sodium chloride ($\text{NaCl}$) using the Down’s cell.
Physical Properties of Alkali Metals
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Softness: They are generally very soft and can easily be cut with a knife.
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Appearance: They display a shiny, silvery-grey surface when freshly cut, but they rapidly tarnish in air and become dull due to oxidation.
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Conductivity: They serve as excellent conductors of both heat and electricity.
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Melting & Boiling Points: They have lower melting and boiling points than other metals because their metallic bonds are relatively weak.
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Mechanical Properties: They are highly malleable (can be hammered into thin sheets) and ductile (can be drawn into thin wires).
Chemical Reactivity of Alkali Metals
Alkali metals are the most reactive metals in the periodic table. They react by losing their single outer valence electron, making them highly electropositive.
Because they all share one valence electron, they exhibit very similar chemical properties. Their chemical reactivity increases as you move down the group:
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Francium ($\text{Fr}$) is the most reactive metal in the group.
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Note: The chemistry of francium is not well established because it is highly radioactive and has only been obtained in minute quantities.
1) Reactions of Alkali Metals with Water
Alkali metals react vigorously with water to produce a metal hydroxide solution and liberate hydrogen gas, which causes noticeable effervescence. The rate and intensity of this reaction increases systematically down the group.
(Where $\text{M}$ represents any alkali metal, such as $\text{Li}$, $\text{Na}$, or $\text{K}$)
