Question

Group the following elements in pairs that you would expect to show similar chemical properties: \(\mathrm{I}, \mathrm{Ba}, \mathrm{O}, \mathrm{Br}\), \(\mathrm{S}\) and \(\mathrm{Ca}\)

Short answer

Pairs are \( (\mathrm{I}, \mathrm{Br}) \), \( (\mathrm{O}, \mathrm{S}) \), and \( (\mathrm{Ba}, \mathrm{Ca}) \).

Step-by-step solution

Identify Chemical Groups

First, determine in which groups (columns) each element is located on the Periodic Table:- \(\mathrm{I} (Iodine)\) and \(\mathrm{Br} (Bromine)\) are both in Group 17, which are halogens.- \(\mathrm{O} (Oxygen)\) and \(\mathrm{S} (Sulfur)\) are in Group 16, which are chalcogens.- \(\mathrm{Ba} (Barium)\) and \(\mathrm{Ca} (Calcium)\) are in Group 2, known as alkaline earth metals.

Pair Elements by Group Similarity

Next, group the elements based on their placement in the same chemical groups:- \(\mathrm{I}\) and \(\mathrm{Br}\) are paired together since they are both halogens with similar chemical behaviors.- \(\mathrm{O}\) and \(\mathrm{S}\) are paired because they are both chalcogens sharing similar reactivity and electronegativity traits.- \(\mathrm{Ba}\) and \(\mathrm{Ca}\) are paired together as both are alkaline earth metals.

Key concepts

Halogens

Halogens are a fascinating group of elements situated in Group 17 of the Periodic Table. This group includes elements like iodine (\(\mathrm{I}\)) and bromine (\(\mathrm{Br}\)). These elements are known for their distinctive and reactive properties. Halogens have seven electrons in their outermost shell, making them highly eager to gain one more electron to achieve a stable electronic configuration, which is similar to that of noble gases. This eagerness to gain an electron makes halogens highly reactive, especially with alkali and alkaline earth metals.

Key characteristics of halogens include:

• **High Reactivity:** They readily form salts, such as sodium chloride (table salt), when they react with metals.
• **Non-metallic Nature:** Halogens are nonmetals with distinctive colors and odors.
• **Existence in Different States:** At room temperature, halogens are found in various states. For instance, chlorine is a gas, bromine is a liquid, and iodine is a solid.
• **Antimicrobial Properties:** Halogens, especially chlorine and iodine, are used in disinfectants and antiseptics because of their ability to kill bacteria and microorganisms.

Understanding halogens is vital as they play significant roles in both biological processes and industrial applications.

Chalcogens

Chalcogens, located in Group 16 of the Periodic Table, comprise elements such as oxygen (\(\mathrm{O}\)) and sulfur (\(\mathrm{S}\)). These elements have six electrons in their outermost shell and typically seek to gain two electrons to achieve stability similar to that of noble gases. This electron gain tendency influences their chemical behavior. Chalcogens are known for forming compounds, particularly oxides and sulfides, due to their strong affinity for combining with other elements.

Important properties of chalcogens include:

• **Diverse Bonding Capabilities:** They can form double bonds such as in \(\mathrm{O}_2\) (oxygen gas) and \(\mathrm{SO}_2\) (sulfur dioxide).
• **Significant Biological Roles:** Oxygen is crucial for respiration, and sulfur is an essential element in proteins.
• **Sulfur's Role in Acid Formation:** Sulfur commonly forms sulfuric acid and its related compounds in industrial settings.
• **Combustion Involvement:** Chalcogens can undergo combustion; for example, sulfur burns to produce sulfur dioxide.

Mastering the concepts of chalcogens gives insight into many natural processes and industrial applications.

Alkaline Earth Metals

Alkaline earth metals, found in Group 2 of the Periodic Table, include elements such as barium (\(\mathrm{Ba}\)) and calcium (\(\mathrm{Ca}\)). These metals are characterized by having two electrons in their outermost shell, making them somewhat reactive, though not as much as Group 1 alkali metals. They readily lose these two outer electrons to form stable cations.

Key aspects of alkaline earth metals include:

• **Moderate Reactivity:** They react with water more slowly than alkali metals, forming hydroxides.
• **Formation of Ionic Compounds:** They form ionic compounds such as calcium carbonate and magnesium oxide.
• **Biological Importance:** Both calcium and magnesium are essential for various biological functions, including bone formation and enzyme activity.
• **Usage in Daily Life:** These metals are used in materials like cement and as dietary supplements to support bone health.

Understanding the chemical properties of alkaline earth metals equips one with the necessary knowledge of their uses and roles in daily life and industrial applications.