1. Question: Discuss the electronic configuration and general characteristics of alkali metals. How does their reactivity change as you move down the group?
Answer: The alkali metals belong to Group 1 of the periodic table and have the general electronic configuration [noble gas] ns1. They are highly reactive due to their low ionization energies and readily lose their valence electron to form a +1 cation. As we move down the group, the reactivity of alkali metals increases due to the decrease in ionization energy and increase in atomic size. This is because the outermost electron is further away from the nucleus, making it easier to remove.
2. Question: Explain the anomalous behavior of lithium among the alkali metals.
Answer: Lithium exhibits some anomalous behavior compared to the other alkali metals. This is primarily due to its small size and high electronegativity. Unlike the other alkali metals, lithium forms a significant amount of covalent compounds and has a higher melting and boiling point. Additionally, lithium has a greater tendency to form Li+ ions rather than losing its valence electron completely. These anomalous properties can be attributed to the strong attraction between the small lithium cation and the surrounding electrons.
3. Question: Discuss the preparation, properties, and uses of sodium hydroxide.
Answer: Sodium hydroxide (NaOH) is prepared by the electrolysis of aqueous sodium chloride (brine) using a diaphragm cell. It is a white, crystalline solid that is highly soluble in water and is a strong base. Sodium hydroxide is widely used in various industries such as soap and detergent manufacturing, paper production, and water treatment. It is also used in the production of various chemicals, including sodium salts, dyes, and pharmaceuticals.
4. Question: Compare and contrast the reactions of alkaline earth metals with water and oxygen.
Answer: Alkaline earth metals react with water and oxygen to form oxides and hydroxides. However, their reactivity differs from that of alkali metals. Alkaline earth metals react with water to form hydroxides and hydrogen gas, but the reaction is slower and less vigorous compared to alkali metals. When exposed to oxygen, alkaline earth metals form oxides. Unlike alkali metals, the reactivity of alkaline earth metals with oxygen increases as you move down the group. Beryllium and magnesium react slowly, while calcium, strontium, and barium react more vigorously with oxygen.
5. Question: Explain the importance of calcium in biological systems.
Answer: Calcium is an essential element for various biological processes. It plays a crucial role in the formation and maintenance of strong bones and teeth. Calcium ions are also involved in muscle contraction, nerve function, and blood clotting. Additionally, calcium is required for the activation of certain enzymes and is involved in cell signaling pathways. A deficiency of calcium can lead to conditions like osteoporosis and muscle cramps.
6. Question: Discuss the preparation, properties, and uses of quicklime (calcium oxide).
Answer: Quicklime (calcium oxide, CaO) is prepared by heating calcium carbonate (limestone) at high temperatures. It is a white, crystalline solid that reacts vigorously with water to form calcium hydroxide. Quicklime is widely used in construction, as a flux in metallurgy, and in the production of cement, glass, and paper. It is also used in the treatment of acidic soils to neutralize acidity.
7. Question: Explain the factors influencing the solubility of alkaline earth metal hydroxides.
Answer: The solubility of alkaline earth metal hydroxides decreases as you move down the group. This is due to the increase in lattice energy, which is the energy required to separate the ions in the solid state. As the size of the metal cation increases, the lattice energy also increases, making it more difficult for the hydroxide ions to dissociate from the metal cation. Additionally, the hydration energy of the metal cation decreases as you move down the group, further reducing the solubility of the hydroxides.
8. Question: Discuss the occurrence and extraction of magnesium from its ores.
Answer: Magnesium is primarily obtained from its ores, such as magnesite (MgCO3) and dolomite (MgCO3.CaCO3). The extraction of magnesium involves the following steps: (1) Calcination: The ore is heated in a kiln to convert it into magnesium oxide. (2) Reduction: The magnesium oxide is then reduced with ferrosilicon or carbon to obtain magnesium vapor. (3) Condensation: The magnesium vapor is condensed to obtain pure magnesium. Magnesium is widely used in the aerospace industry, as an alloying agent, and in the production of lightweight materials.
9. Question: Explain the biological role of magnesium in plants and animals.
Answer: Magnesium is essential for the growth and development of plants. It is a component of chlorophyll, the pigment responsible for photosynthesis. Magnesium also plays a role in activating various enzymes involved in carbohydrate metabolism and protein synthesis. In animals, magnesium is required for muscle and nerve function, DNA and RNA synthesis, and the regulation of blood pressure. Deficiency of magnesium can lead to muscle weakness, cardiac arrhythmias, and impaired bone health.
10. Question: Discuss the uses of beryllium and its compounds.
Answer: Beryllium and its compounds have several industrial applications. Beryllium metal is used in the aerospace industry due to its high strength-to-weight ratio and excellent thermal conductivity. Beryllium-copper alloys are used in electrical connectors and switches. Beryllium oxide is used as a ceramic material in high-performance electronics and nuclear reactors. However, it is important to note that beryllium and its compounds are highly toxic and can cause a serious lung disease called berylliosis. Strict safety precautions must be taken when handling beryllium.