s and p Block Elements
36 Questions
3 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

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?

  • Superoxides of alkali metals
  • Oxides of alkali metals
  • Peroxides of alkali metals
  • Hydrides of alkali metals (correct)

    • 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?

    <p>Strong oxidising agents (C)</p> Signup and view all the answers

    How does the reactivity of alkali metals towards air and water change from Li to Cs?

    <p>It increases (D)</p> Signup and view all the answers

    What is the nature of the solutions formed when carbonates and bicarbonates of alkali metals are dissolved in water?

    <p>Alkaline (B)</p> Signup and view all the answers

    What is the density of Lithium at 200°C?

    <p>0.534 g/ml (D)</p> Signup and view all the answers

    Why is Potassium lighter than Sodium?

    <p>Due to its unusually large atomic size (C)</p> Signup and view all the answers

    What is the crystal structure of alkali metals in their solid state?

    <p>Body-centred cubic lattice (B)</p> Signup and view all the answers

    Why are alkali metal salts colourless and diamagnetic?

    <p>Because they have ns0 configuration (D)</p> Signup and view all the answers

    What is the trend of atomic and ionic radii of alkali metals down the group?

    <p>They increase down the group (B)</p> Signup and view all the answers

    What are the physical properties of alkali metals?

    <p>They are silvery white, soft and light solids (C)</p> Signup and view all the answers

    What is the primary reason behind the high oxidation potential of alkali metals?

    <p>Their ability to easily lose an ns1 electron (A)</p> Signup and view all the answers

    Which of the following alkali metals has the maximum tendency to liberate H2 from H2O and HCl?

    <p>Lithium (D)</p> Signup and view all the answers

    Why do lithium salts tend to be hydrated?

    <p>Due to their high degree of hydration and small size (A)</p> Signup and view all the answers

    What is the reason behind the poor conductivity of lithium ions in an electric field?

    <p>Their high degree of hydration (D)</p> Signup and view all the answers

    What is the property of alkali metal salts that can be attributed to their M+ ions having no unpaired electrons?

    <p>Diamagnetism (A)</p> Signup and view all the answers

    What is the general trend observed in the standard oxidation potentials of alkali metals?

    <p>They increase from Li to Cs (A)</p> Signup and view all the answers

    What is the primary reason behind the increase in concentration of OH– ions in alkali metal hydroxides down the group?

    <p>Increase in ionic character of alkali metal hydroxides (B)</p> Signup and view all the answers

    What is the nature of the hydrides formed by alkali metals, such as NaBH4 and LiAlH4?

    <p>Good reducing agents (D)</p> Signup and view all the answers

    What is the product formed at the anode during the electrolysis of fused alkali metal hydroxides?

    <p>O2(g) (D)</p> Signup and view all the answers

    What is the trend observed in the reactivity of alkali metals towards air and water from Li to Cs?

    <p>Increases rapidly (D)</p> Signup and view all the answers

    What is the characteristic of the solutions formed when alkali metal carbonates and bicarbonates are dissolved in water?

    <p>Basic (D)</p> Signup and view all the answers

    What is the reason behind the stability of alkali metal carbonates and bicarbonates to heat?

    <p>Increase in electropositive character of alkali metals (B)</p> Signup and view all the answers

    What is the reason behind the powerful reducing nature of alkali metals in aqueous medium?

    <p>Maximum hydration energy of Li+ ion (D)</p> Signup and view all the answers

    Which of the following is responsible for the poor conductivity of lithium ions in an electric field?

    <p>Heavy hydration of Li+ ion (B)</p> Signup and view all the answers

    What is the trend observed in the standard oxidation potentials of alkali metals?

    <p>Increasing from Li to Cs (C)</p> Signup and view all the answers

    Why do alkali metal salts tend to be colourless and diamagnetic?

    <p>Due to the absence of unpaired electrons in M+ ions (B)</p> Signup and view all the answers

    What is the reason behind the high oxidation potential of alkali metals?

    <p>Easy loss of ns1 electron by alkali metals (B)</p> Signup and view all the answers

    What is the general trend observed in the ionic radii of alkali metals?

    <p>Increasing from Li to Cs (B)</p> Signup and view all the answers

    Which of the following alkali metals has the highest density at 200°C?

    <p>Caesium (D)</p> Signup and view all the answers

    Why do alkali metals have low melting and boiling points compared to other group members?

    <p>Due to their large atomic size (C)</p> Signup and view all the answers

    What is the main reason behind the colourless and diamagnetic nature of alkali metal salts?

    <p>Due to the absence of unpaired electrons (C)</p> Signup and view all the answers

    What is the crystal structure of alkali metals in their solid state?

    <p>Body-centred cubic lattice (B)</p> Signup and view all the answers

    Why do alkali metals have the largest atomic and ionic radii among their successive elements of the same period?

    <p>Due to the addition of new energy shells (D)</p> Signup and view all the answers

    What is the physical appearance of alkali metals?

    <p>Silvery white, soft, and light (A)</p> Signup and view all the answers

    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.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Chapter 18: Alkali Metals and Their Compounds PDF

    Description

    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.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser