Question

Which of the following statements is falsc? (1) Strontium decomposes water readily than beryllium. (2) Barium carbonate decomposes at a higher temperature than calcium carbonate. (3) Barium hydroxide is more soluble in water than magnesium hydroxide. (4) Barium hydroxide is less basic than magnesium hydroxide.

Short answer

The false statement is (4).

Step-by-step solution

- Analyze the First Statement

Strontium decomposes water more readily than beryllium. This statement is true because strontium is an alkaline earth metal located below beryllium in the periodic table, making it more reactive with water.

- Evaluate the Second Statement

Barium carbonate decomposes at a higher temperature than calcium carbonate. This statement is true because, generally, the decomposition temperature of carbonates increases down the group in alkaline earth metals.

- Verify the Third Statement

Barium hydroxide is more soluble in water than magnesium hydroxide. This statement is true because the solubility of hydroxides of alkaline earth metals increases down the group.

- Check the Fourth Statement

Barium hydroxide is less basic than magnesium hydroxide. This statement is false because barium hydroxide is more basic than magnesium hydroxide; alkalinity increases down the group in alkaline earth metals.

Key concepts

periodic table trends

Periodic table trends refer to the predictable patterns observed in the properties of elements as one moves across or down the periodic table. Among these trends, reactivity and atomic size are particularly important. As you move from left to right across a period, elements generally become less metallic, more electronegative, and have higher ionization energies. Going down a group, elements typically become more reactive, especially in the case of metals. For example, in the alkaline earth metals group, reactivity increases as you move from beryllium (higher up) to barium (lower down). This is because the outermost electrons are farther from the nucleus and are more easily lost during chemical reactions.

alkaline earth metals

Alkaline earth metals include the elements in Group 2 of the periodic table: beryllium, magnesium, calcium, strontium, barium, and radium. These metals are characterized by having two electrons in their outermost shell, which they readily lose to form +2 cations. Their physical properties include being shiny and silver-white, and they tend to have higher melting points than alkali metals. Chemically, they are highly reactive, though less so than alkali metals. As you go down the group from beryllium to barium, the elements become more reactive, their atomic and ionic sizes increase, and they have a lower ionization energy, making it easier for them to lose electrons.

solubility of hydroxides

The solubility of hydroxides in water increases as you move down the group in alkaline earth metals. This means that barium hydroxide is more soluble in water than magnesium hydroxide. Solubility trends are influenced by the lattice energy of the hydroxide crystal and the hydration energy of the ions. The larger the metal ion, the lower its lattice energy and the easier it is for water to dissolve the compound. Hence, barium hydroxide (Ba(OH)₂) dissolves readily in water, while magnesium hydroxide (Mg(OH)₂) is only sparingly soluble. This understanding is crucial for practical applications such as wastewater treatment and chemical synthesis.

thermal decomposition of carbonates

Thermal decomposition is the process where a chemical compound breaks down into simpler substances when heated. For alkaline earth metal carbonates, the decomposition temperature increases as you go down the group. In simpler terms, barium carbonate requires a higher temperature to decompose compared to calcium carbonate. This occurs because the lattice energy of carbonates decreases down the group, making it increasingly difficult to break the bonds holding the ions together. Thus, Barium carbonate (BaCO₃) remains stable at higher temperatures, whereas calcium carbonate (CaCO₃) decomposes into calcium oxide (CaO) and carbon dioxide (CO₂) at relatively lower temperatures.