Problem 88 - Chemistry The Molecular Science

Question

Ten of the elements are \(\mathrm{O}, \mathrm{H}, \mathrm{Ar}, \mathrm{Al}, \mathrm{Ca}, \mathrm{Br}, \mathrm{Ge}, \mathrm{K}, \mathrm{Cu}\) and \(P\). Pick the one that best fits each description: (a) an alkali metal; (b) a noble gas; (c) a transition metal; (d) a metalloid; (e) a Group 1 nonmetal; (f) an alkaline-earth metal; \((\mathrm{g})\) a halogen; (h) a nonmetal that is a solid.

Step-by-Step Solution

Answer

K is an alkali metal, Ar a noble gas, Cu a transition metal, Ge a metalloid, H a Group 1 nonmetal, Ca an alkaline-earth metal, Br a halogen, and P a solid nonmetal.

Step 1: Identify the Alkali Metal

The alkali metals are found in Group 1 of the periodic table and are known for being very reactive metals. Given the elements, K (Potassium) is the alkali metal.

Step 2: Identify the Noble Gas

Noble gases are located in Group 18 and are characterized by their lack of reactivity due to having full valence electron shells. Given the elements, Ar (Argon) is the noble gas.

Step 3: Identify the Transition Metal

Transition metals are found in the center of the periodic table, specifically in groups 3 through 12. Cu (Copper) fits this category as it is a transition metal.

Step 4: Identify the Metalloid

Metalloids have properties intermediate between metals and nonmetals and are found along the diagonal line of the periodic table. Ge (Germanium) is the metalloid among the given elements.

Step 5: Identify the Group 1 Nonmetal

In Group 1, one might expect only metals, but hydrogen is a unique case as a nonmetal in this group. H (Hydrogen) is the Group 1 nonmetal.

Step 6: Identify the Alkaline-Earth Metal

Alkaline-earth metals are found in Group 2 of the periodic table and include Ca (Calcium) among the listed elements.

Step 7: Identify the Halogen

Halogens are found in Group 17 and are known for their reactive nonmetallic properties. Br (Bromine) is the halogen among these elements.

Step 8: Identify the Nonmetal that is a Solid

Solid nonmetals are found in the periodic table's upper right portion. Among these elements, P (Phosphorus) is known as a solid and a nonmetal.

Key Concepts

Alkali Metal

Alkali metals are fascinating elements located in **Group 1** of the periodic table. These metals are known for their high reactivity, especially with water, and are never found in their free form in nature. This group includes elements like lithium, sodium, and potassium. Among the given elements, **Potassium (K)** is the alkali metal.

• Characteristics: Shiny, soft, highly reactive.
• Examples: Lithium (Li), Sodium (Na), Potassium (K).

Their high reactivity is due to having one electron in their outermost shell, which they readily lose to achieve a stable noble gas electron configuration. They are essential in various biological processes and have industrial uses.

Noble Gas

Noble gases are a unique group of non-reactive elements located in **Group 18** of the periodic table. These gases are characterized by their full valence electron shells, making them very stable and inert. Among the listed elements, **Argon (Ar)** is a noble gas.

• Characteristics: Colorless, odorless, nonreactive.
• Examples: Helium (He), Neon (Ne), Argon (Ar).

Noble gases are used in lighting, welding, and as a protective atmosphere for chemical reactions due to their stability. They do not easily form compounds under normal conditions.

Transition Metal

Transition metals are located in the center of the periodic table, spanning **Groups 3 to 12**. These elements are characterized by their ability to form various oxidation states and colored compounds. From the elements provided, **Copper (Cu)** fits this description.

• Characteristics: Conductive, malleable, exhibit variable oxidation states.
• Examples: Iron (Fe), Copper (Cu), Nickel (Ni).

Transition metals are essential in everyday materials from coins to electrical devices, due to their excellent conductive properties. They often serve as catalysts in chemical reactions due to their stable yet variable electronic configurations.

Metalloid

Metalloids are elements that have properties in between metals and nonmetals, often making them versatile for various applications. They are found along a diagonal line between metals and nonmetals in the periodic table. Here, **Germanium (Ge)** is identified as the metalloid.

• Characteristics: Semi-conductive, brittle, metallic luster.
• Examples: Silicon (Si), Germanium (Ge), Arsenic (As).

Metalloids are widely used in the technology industry, particularly in semiconductors and electronic components, where their ability to conduct electricity can be adjusted through doping.

Group 1 Nonmetal

In Group 1 of the periodic table, which is predominately metals, there is a unique nonmetal—**Hydrogen (H)**. Unlike the other group members, hydrogen is a light, reactive nonmetal.

• Characteristics: Colorless gas, highly flammable, diatomic molecule (H₂).
• Examples: Hydrogen (H).

Hydrogen plays a crucial role in the universe as the simplest and most abundant element and is a key player in chemical reactions, including the formation of water and organic compounds. It is a primary fuel source and potential clean energy.

Alkaline-Earth Metal

Alkaline-earth metals are found in **Group 2** of the periodic table and are known for their two positive oxidation states. These metals are reactive, but not as much as alkali metals. Among our list of elements, **Calcium (Ca)** is an alkaline-earth metal.

• Characteristics: Shiny, somewhat reactive, form oxides readily.
• Examples: Magnesium (Mg), Calcium (Ca), Barium (Ba).

These metals are essential for life and are found in various minerals. Calcium, for example, is critical for biological functions such as bone and dental health and is a component in concrete and antacids.

Halogen

Halogens, found in **Group 17** of the periodic table, are highly reactive nonmetals. They are known for forming salts when they react with metals. **Bromine (Br)** is the halogen among the provided elements.

• Characteristics: Reactive, form diatomic molecules (F₂, Cl₂), exist in all three states of matter at room temperature.
• Examples: Fluorine (F), Chlorine (Cl), Bromine (Br).

Halogens are commonly used in disinfection, dental health (fluoride in toothpaste), and preparation of various useful compounds. Their reactivity allows them to form compounds with a wide range of substances, including organic molecules.

Solid Nonmetal

Solid nonmetals are typically located in the upper right section of the periodic table. They do not conduct electricity well and have higher electronegativities. Among the given elements, **Phosphorus (P)** is a solid nonmetal.

• Characteristics: Brittle, high ionization energies, insulating.
• Examples: Carbon (C), Sulfur (S), Phosphorus (P).

These nonmetals are crucial for biological structures and organic chemistry. Phosphorus, specifically, is vital for life as part of DNA, ATP, and cellular membranes. It is also widely used in fertilizers and match production due to its reactivity and role in energy transfer processes.