Question

Which of the following statements is false? (1) \(\Lambda\) lkaline carth metals are weaker reducing agents than alkali metals becausc of their comparatively high ionization cncrgics. (2) The reducing nature of alkaline carth metals follows the incrcasing order as \(\mathrm{Be}<\mathrm{Mg}<\mathrm{Ca}<\) \(\mathrm{Sr}<\mathrm{Ba}\) (3) Compounds of II group clements are colourless and diamagnctic duc to the abscnce of umpaircd clcctrons. (4) \Lambdalkaline carth metals have low clectrical and thermal conductivitics than alkali metals.

Short answer

Statement 4 is false.

Step-by-step solution

- Understand the Statements

Read through each statement carefully to understand what is being claimed about the properties of alkaline earth metals and alkali metals.

- Verify Statement 1

Statement 1 claims that alkaline earth metals are weaker reducing agents than alkali metals due to their higher ionization energies. This is true, as alkaline earth metals have higher ionization energies than alkali metals, making them less likely to lose electrons and thus weaker reducing agents.

- Verify Statement 2

Statement 2 claims that the reducing nature of alkaline earth metals follows the order \(\mathrm{Be}<\mathrm{Mg}<\mathrm{Ca}<\mathrm{Sr}<\mathrm{Ba}\). This is true; as you go down the group, the ionization energy decreases and the reducing nature increases.

- Verify Statement 3

Statement 3 states that compounds of group II elements are colorless and diamagnetic due to the absence of unpaired electrons. This is true because group II elements typically form compounds with fully paired electrons, resulting in colorless and diamagnetic properties.

- Verify Statement 4

Statement 4 suggests that alkaline earth metals have lower electrical and thermal conductivities than alkali metals. This is false. Alkaline earth metals typically have higher electrical and thermal conductivities compared to alkali metals.

Conclusion

Based on the analysis of each statement, Statement 4 is false.

Key concepts

alkaline earth metals

Alkaline earth metals belong to Group 2 of the periodic table. They include Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), and Barium (Ba). Each of these metals has two electrons in their outermost shell, which results in their typical +2 oxidation state in compounds. These metals are shiny and have a silvery-white appearance. They are also relatively reactive, though less so than their Group 1 counterparts, the alkali metals.

• They react with water, though reactions vary in intensity.
• They form oxides and hydroxides that are basic.
• They have high melting and boiling points relative to alkali metals.

Their reactivity increases down the group as it becomes easier to lose the two outer electrons.

reducing agents

A reducing agent, or reductant, is a substance that donates electrons to another substance in a chemical reaction. This process is known as reduction. Alkaline earth metals can act as reducing agents because they tend to lose electrons easily, especially as you move down the group in the periodic table.

• Reductants lose electrons and become oxidized.
• They typically reduce oxidizing agents while themselves being oxidized.

For instance, among alkaline earth metals, Beryllium (Be) is a weaker reducing agent compared to Barium (Ba) because it has a higher ionization energy, making it less willing to lose its electrons.

ionization energy

Ionization energy is the amount of energy needed to remove one mole of electrons from one mole of isolated gaseous atoms or ions. In the context of alkaline earth metals, ionization energy decreases as you move down the group. This means it's easier to remove an electron from Barium (Ba) than from Beryllium (Be).

• First ionization energy involves removing the first electron.
• Second ionization energy involves removing the second electron.

Since alkaline earth metals have higher ionization energies compared to alkali metals, they are less likely to lose electrons and thus are weaker reducing agents.

electrical conductivity

Electrical conductivity refers to a material's ability to conduct an electric current. Alkaline earth metals generally have good electrical conductivity, though not as high as alkali metals. Conductivity is influenced by the metallic bonds and the number of free electrons available in the structure.

• Alkaline earth metals provide two free electrons per atom for electrical conduction.
• Electrical conductivity usually goes up as you move down the group because the metals become more reactive.

For example, Magnesium (Mg) conducts electricity well, but Calcium (Ca), being lower in the group, conducts even better due to its more reactive nature.

thermodynamics

Thermodynamics in chemistry involves studying the energy changes that occur during chemical reactions. For alkaline earth metals, several thermodynamic aspects are considered, such as enthalpy of formation, Gibbs free energy, and entropy.

• The enthalpy of formation for alkaline earth metals becomes more negative as you move down the group.
• Gibbs free energy change indicates the spontaneity of reactions.
• Entropy measures the disorder or randomness in a system.

Metals like Calcium (Ca) and Barium (Ba) often show more negative enthalpy values, making their compounds more thermodynamically stable compared to Beryllium (Be) and Magnesium (Mg).