Question

Compare the elements silicon (Si) and phosphorus (P) using the following criteria: (a) metal, metalloid, or nonmetal (b) possible conductor of electricity (c) physical state at \(25^{\circ} \mathrm{C}\) (solid, liquid, or gas)

Short answer

Silicon (Si) is a metalloid and semiconductor, solid at 25°C. Phosphorus (P) is a nonmetal and insulator, also solid at 25°C.

Step-by-step solution

Identify as Metal, Metalloid, or Nonmetal

**Silicon (Si):** Silicon is classified as a metalloid. **Phosphorus (P):** Phosphorus is classified as a nonmetal.

Assess Electrical Conductivity

**Silicon (Si):** Silicon is a semiconductor and can conduct electricity under certain conditions, which is characteristic of metalloids. **Phosphorus (P):** Phosphorus is a nonmetal and does not conduct electricity well; it is an insulator.

Determine Physical State at Room Temperature

**Silicon (Si):** At room temperature (25°C), silicon is a solid. **Phosphorus (P):** At room temperature, phosphorus is also a solid, although it has different allotropes (e.g., white and red phosphorus) that vary in stability.

Key concepts

Metals

Metals are known for their shiny appearance and are typically very good conductors of electricity and heat. They are malleable and ductile, allowing them to be shaped without breaking.
Examples of metals include iron, copper, and gold. These elements usually lose electrons and form positive ions.

• **Appearance:** Shiny and lustrous surfaces.
• **Conductivity:** Excellent conductors of electricity and heat.
• **Malleability:** Can be hammered or rolled into thin sheets.

Although silicon is not a metal, its properties are often compared with metals due to its ability to conduct electricity under certain conditions.

Metalloids

Metalloids have properties that are intermediate between metals and nonmetals. Silicon (Si), for instance, is a metalloid.
It is crucial in the technology industry, specifically in semiconductors and computer components. Metalloids can have varying abilities to conduct electricity, often dependent on external factors like temperature or the presence of an electric field.

• **Conductivity:** They can act as conductors under certain conditions.
  This makes them valuable in the electronics industry.
• **Appearance:** Often look like metals but are brittle.
• **Flexibility:** Less malleable compared to metals.

Metalloids are fascinating because their properties make them highly adaptable in various applications.

Nonmetals

Nonmetals are very different from metals and metalloids. They are not good conductors of heat or electricity. Phosphorus (P) is a nonmetal, making it typically a poor conductor, functioning more like an insulator.
Nonmetals can exist in various physical states at room temperature: some as gases (e.g., oxygen), some as solids (e.g., sulfur), and others as liquids under specific conditions.

• **Conductivity:** Generally poor conductors, except in cases where they form compounds.
• **Physical States:** More diverse; can be solids, liquids, or gases at room temperature.
• **Reactivity:** Highly variable; some nonmetals are very reactive while others are inert.

Their properties also make them essential in biological and chemical processes.

Semiconductors

Semiconductors are materials that have conduction abilities between metals and insulators. A great example of a semiconductor is silicon (Si).
Silicon is critical in the production of electronic circuits and devices due to its ability to conduct electricity variably. The conductivity of a semiconductor can be altered by introducing impurities, a process called doping.

• **Variable Conductivity:** Their ability to conduct electricity can be precisely controlled.
• **Key Usage:** Widely used in electronic devices like computers and smartphones.
• **Doping:** Modifying electrical properties by adding trace amounts of other elements.

Semiconductors lie at the heart of modern technology, forming the backbone of contemporary electronic systems.

Allotropes

Allotropes refer to different structural forms of the same element within the same physical state. Phosphorus demonstrates this through its various allotropes, such as white phosphorus and red phosphorus, which differ significantly in their properties and stability.
Allotropes can greatly influence how an element behaves in different chemical reactions and practical applications.

• **Examples:** Oxygen has allotropes such as O₂ (oxygen gas) and O₃ (ozone).
• **Properties:** Different allotropes of an element can have vastly different chemical and physical properties.
• **Impact:** Allotropes can change the reactivity and interaction with other elements and compounds.

Understanding allotropes helps in comprehending the dynamic nature of elements and their applications.