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Questions and Answers
What is the reason for the increase in ionic character of alkali metal hydroxides down the group?
What is the reason for the increase in ionic character of alkali metal hydroxides down the group?
- Due to increase in atomic size
- Due to decrease in electropositive character
- Due to decrease in atomic size
- Due to increase in electropositive character (correct)
What are NaBH4 and LiAlH4 examples of?
What are NaBH4 and LiAlH4 examples of?
- Superoxides of alkali metals
- Oxides of alkali metals
- Peroxides of alkali metals
- Hydrides of alkali metals (correct)
What happens when Li2CO3 is heated?
What happens when Li2CO3 is heated?
- It remains unaffected
- It decomposes into Li2O and CO2 (correct)
- It reacts with water to form LiOH
- It dissolves in water to form Li2CO3(aq)
What is the nature of the peroxides and superoxides of alkali metals?
What is the nature of the peroxides and superoxides of alkali metals?
How does the reactivity of alkali metals towards air and water change from Li to Cs?
How does the reactivity of alkali metals towards air and water change from Li to Cs?
What is the nature of the solutions formed when carbonates and bicarbonates of alkali metals are dissolved in water?
What is the nature of the solutions formed when carbonates and bicarbonates of alkali metals are dissolved in water?
What is the density of Lithium at 200°C?
What is the density of Lithium at 200°C?
Why is Potassium lighter than Sodium?
Why is Potassium lighter than Sodium?
What is the crystal structure of alkali metals in their solid state?
What is the crystal structure of alkali metals in their solid state?
Why are alkali metal salts colourless and diamagnetic?
Why are alkali metal salts colourless and diamagnetic?
What is the trend of atomic and ionic radii of alkali metals down the group?
What is the trend of atomic and ionic radii of alkali metals down the group?
What are the physical properties of alkali metals?
What are the physical properties of alkali metals?
What is the primary reason behind the high oxidation potential of alkali metals?
What is the primary reason behind the high oxidation potential of alkali metals?
Which of the following alkali metals has the maximum tendency to liberate H2 from H2O and HCl?
Which of the following alkali metals has the maximum tendency to liberate H2 from H2O and HCl?
Why do lithium salts tend to be hydrated?
Why do lithium salts tend to be hydrated?
What is the reason behind the poor conductivity of lithium ions in an electric field?
What is the reason behind the poor conductivity of lithium ions in an electric field?
What is the property of alkali metal salts that can be attributed to their M+ ions having no unpaired electrons?
What is the property of alkali metal salts that can be attributed to their M+ ions having no unpaired electrons?
What is the general trend observed in the standard oxidation potentials of alkali metals?
What is the general trend observed in the standard oxidation potentials of alkali metals?
What is the primary reason behind the increase in concentration of OH– ions in alkali metal hydroxides down the group?
What is the primary reason behind the increase in concentration of OH– ions in alkali metal hydroxides down the group?
What is the nature of the hydrides formed by alkali metals, such as NaBH4 and LiAlH4?
What is the nature of the hydrides formed by alkali metals, such as NaBH4 and LiAlH4?
What is the product formed at the anode during the electrolysis of fused alkali metal hydroxides?
What is the product formed at the anode during the electrolysis of fused alkali metal hydroxides?
What is the trend observed in the reactivity of alkali metals towards air and water from Li to Cs?
What is the trend observed in the reactivity of alkali metals towards air and water from Li to Cs?
What is the characteristic of the solutions formed when alkali metal carbonates and bicarbonates are dissolved in water?
What is the characteristic of the solutions formed when alkali metal carbonates and bicarbonates are dissolved in water?
What is the reason behind the stability of alkali metal carbonates and bicarbonates to heat?
What is the reason behind the stability of alkali metal carbonates and bicarbonates to heat?
What is the reason behind the powerful reducing nature of alkali metals in aqueous medium?
What is the reason behind the powerful reducing nature of alkali metals in aqueous medium?
Which of the following is responsible for the poor conductivity of lithium ions in an electric field?
Which of the following is responsible for the poor conductivity of lithium ions in an electric field?
What is the trend observed in the standard oxidation potentials of alkali metals?
What is the trend observed in the standard oxidation potentials of alkali metals?
Why do alkali metal salts tend to be colourless and diamagnetic?
Why do alkali metal salts tend to be colourless and diamagnetic?
What is the reason behind the high oxidation potential of alkali metals?
What is the reason behind the high oxidation potential of alkali metals?
What is the general trend observed in the ionic radii of alkali metals?
What is the general trend observed in the ionic radii of alkali metals?
Which of the following alkali metals has the highest density at 200°C?
Which of the following alkali metals has the highest density at 200°C?
Why do alkali metals have low melting and boiling points compared to other group members?
Why do alkali metals have low melting and boiling points compared to other group members?
What is the main reason behind the colourless and diamagnetic nature of alkali metal salts?
What is the main reason behind the colourless and diamagnetic nature of alkali metal salts?
What is the crystal structure of alkali metals in their solid state?
What is the crystal structure of alkali metals in their solid state?
Why do alkali metals have the largest atomic and ionic radii among their successive elements of the same period?
Why do alkali metals have the largest atomic and ionic radii among their successive elements of the same period?
What is the physical appearance of alkali metals?
What is the physical appearance of alkali metals?
Study Notes
Chemical Properties
- Alkali metal hydroxides increase in ionic character down the group, leading to complete dissociation and an increase in OH- ion concentration.
- Alkali metals form hydrides like NaBH4 and LiAlH4, which are good reducing agents.
- Carbonates (M2CO3) and bicarbonates (MHCO3) are highly stable to heat, with stability increasing with electropositive character from Li to Cs.
- Bicarbonates are decomposed at relatively low temperatures, releasing CO2 and H2O.
- Peroxides and superoxides act as strong oxidizing agents due to the formation of H2O2.
Reactivity
- Alkali metals react with air and water, increasing in reactivity from Li to Cs.
- Lithium decomposes H2O slowly at 25°C, while Na reacts vigorously, and K, Rb, and Cs react explosively.
Physical Properties
- Density increases gradually from Li to Cs, with Li being the lightest known metal (0.534 g/ml at 200°C).
- K is lighter than Na due to its unusually large atomic size.
- Alkali metals have a body-centered cubic lattice in the solid state.
Atomic and Ionic Radii
- Alkali metals have the largest atomic and ionic radii among elements in the same period.
- Atomic and ionic radii increase down the group due to the progressive addition of new energy shells.
Melting and Boiling Points
- Alkali metals have low melting and boiling points compared to other group members.
Standard Oxidation Potential and Reduction Properties
- Alkali metals easily lose their ns1 electron, resulting in high oxidation potential values.
- The standard oxidation potentials of alkali metals are listed as: Li (+3.05), Na (+2.71), K (+2.93), Rb (+2.99), and Cs (+2.99).
- The reducing nature of alkali metals increases with oxidation potential, liberating H2 from H2O and HCl.
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Test your knowledge on the chemical properties of alkali metals, including their ionic character, hydrides, carbonates, and bicarbonates. Learn about their stability, reducing agents, and more.
