Question

Match each of the elements on the right with its description on the left: (a) A pale yellow gas that reacts with water \(\quad\) Nitrogen \(\left(\mathrm{N}_{2}\right)\) (b) A soft metal that reacts with water to \(\quad\) Boron \((\mathrm{B})\) produce hydrogen Fluorine \(\left(\mathrm{F}_{2}\right)\) (c) A metalloid that is hard and has a high Aluminum (Al) melting point Sodium (Na) (d) A colorless, odorless gas (e) A metal that is more reactive than iron, but does not corrode in air

Short answer

(a) Fluorine, (b) Sodium, (c) Boron, (d) Nitrogen, (e) Aluminum.

Step-by-step solution

Analyze the descriptions on the left

We need to understand the descriptions given to match them to the right elements. \( \text{(a)} \) A pale yellow gas that reacts with water suggests an active non-metal. \( \text{(b)} \) A soft metal that reacts with water to produce hydrogen indicates an alkali metal. \( \text{(c)} \) A metalloid that is hard with a high melting point points towards elements that have properties of both metals and non-metals. \( \text{(d)} \) A colorless, odorless gas typically describes inert gases or diatomic molecules. \( \text{(e)} \) A metal that is more reactive than iron but doesn't corrode easily is a clue related to protective metallic oxidation.

Match the descriptions with the correct element

Using the analysis, we match each description:- \( \text{(a)} \) should be Fluorine \((\mathrm{F}_{2})\), as it is a pale yellow gas.- \( \text{(b)} \) should be Sodium \((\mathrm{Na})\), since it is a soft metal that reacts with water to release hydrogen.- \( \text{(c)} \) should be Boron \((\mathrm{B})\), identified as a hard metalloid with a high melting point.- \( \text{(d)} \) should be Nitrogen \((\mathrm{N}_{2})\), known as a colorless, odorless gas.- \( \text{(e)} \) should be Aluminum \((\mathrm{Al})\), known to be more reactive than iron but doesn't corrode due to the formation of a protective oxide layer.

Key concepts

Reactivity with Water

When we talk about an element's reactivity with water, we're referring to how it behaves when it comes into contact with water molecules. Some elements, especially alkali metals like sodium, react vigorously.

• Sodium (\( ext{Na} )\) is a classic example of a reactive metal. It's soft and easily cut with a knife.
• When sodium meets water, it reacts exothermically, producing heat, hydrogen gas, and forming sodium hydroxide.
• This can be represented by the chemical equation:\[ ext{2Na} + ext{2H}_2 ext{O} ightarrow ext{2NaOH} + ext{H}_2 \]

The reaction can be quite intense, sometimes even causing flames due to the heat generated. The hydrogen produced can ignite in the air. Not all elements react with water like sodium does, but understanding this property helps in identifying and using these metals carefully.

Metalloids

Metalloids are fascinating elements that have properties of both metals and non-metals. They sit on the dividing line in the periodic table and exhibit unique characteristics.

• An example of a metalloid is Boron (\( ext{B} )\), which is hard and has a very high melting point.
• Unlike most non-metals, boron conducts electricity at certain temperatures and conditions.
• These elements like boron are used in semiconductors due to their ability to conduct electricity better than non-metals, but still control the flow of electric current.
• Metalloids often find application in technology and materials science.

Understanding metalloids and their in-between nature of properties can be crucial in materials engineering and electronics.

Gas Characteristics

Gases have specific characteristics that define their behavior and properties in nature. Many gases are colorless and odorless, making them difficult to detect without special equipment.

• An example is Nitrogen (\( ext{N}_2 )\), which constitutes about 78% of the Earth's atmosphere.
• Nitrogen is colorless and odorless, in line with many descriptions of inert or less reactive gases.
• Though non-reactive at room temperature, nitrogen can form compounds at high temperatures or pressures.

Finding and identifying gases requires an understanding of these properties, making them essential in fields like chemistry and environmental science.

Oxide Layer Protection

Some metals react with oxygen to form a protective oxide layer on their surface. This layer guards the metal underneath from further corrosion or oxidation.

• Aluminum (\( ext{Al} )\) is a prime example of a metal that exploits oxide layer formation.
• When exposed to air, aluminum reacts with oxygen to form aluminum oxide (\( ext{Al}_2 ext{O}_3 )\).
• The formed aluminum oxide is tough and adheres well to the surface, preventing further oxygen from reaching the metal below.
• This protection is why aluminum doesn’t corrode easily and is used in various applications where durability is essential.

Understanding this process is crucial in metallurgy and materials science for developing corrosion-resistant materials.