Problem 89 - Chemistry and Chemical Reactivity

Question

For each of the third-period elements (Na through Ar), identify the following: (a) whether the element is a metal, nonmetal, or metalloid (b) the color and appearance of the element (c) the state of the element \((s, \ell, \text { or } g\) ) under standard conditions

Step-by-Step Solution

Answer

Na, Mg, Al are metals and solids; Si is a metalloid and solid; P, S are nonmetals and solids; Cl is a nonmetal and gas; Ar is a nonmetal and gas.

Step 1: List Third-Period Elements

The third-period elements in the periodic table are sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), and argon (Ar).

Step 2: Classify Each Element as Metal, Nonmetal, or Metalloid

- Sodium (Na), magnesium (Mg), and aluminum (Al) are metals. - Silicon (Si) is a metalloid. - Phosphorus (P), sulfur (S), chlorine (Cl), and argon (Ar) are nonmetals.

Step 3: Determine Color and Appearance

- Sodium (Na): Silvery-white, metallic. - Magnesium (Mg): Silvery-white, metallic. - Aluminum (Al): Silvery-white, metallic. - Silicon (Si): Dark gray with a bluish tint, metallic luster. - Phosphorus (P): Red (common form), nonmetallic. - Sulfur (S): Yellow, nonmetallic. - Chlorine (Cl): Pale yellow-green gas. - Argon (Ar): Colorless gas.

Step 4: Identify State Under Standard Conditions

- Sodium (Na): Solid. - Magnesium (Mg): Solid. - Aluminum (Al): Solid. - Silicon (Si): Solid. - Phosphorus (P): Solid. - Sulfur (S): Solid. - Chlorine (Cl): Gas. - Argon (Ar): Gas.

Key Concepts

Third-period elements

The third-period elements of the periodic table include a fascinating group of elements stretching from Sodium (Na) to Argon (Ar). These elements are unique because they all belong to the third row of the periodic table, which translates into them having three electron shells.

• Sodium (Na)
• Magnesium (Mg)
• Aluminum (Al)
• Silicon (Si)
• Phosphorus (P)
• Sulfur (S)
• Chlorine (Cl)
• Argon (Ar)

These elements display a range of properties and comprise metals, a metalloid, and nonmetals. This diversity is due to the arrangement of electrons that significantly impacts their chemical reactivity and bonding characteristics.

Metal and nonmetal classification

In understanding the periodic table, classifying elements as metals, nonmetals, or metalloids is vital. In the third period, there is a clear distinction between these types:

• Metals: Sodium (Na), Magnesium (Mg), and Aluminum (Al) are metals. They exhibit characteristics such as high electrical conductivity, malleability, and a shiny appearance.
• Metalloid: Silicon (Si) acts as a bridge between metals and nonmetals, possessing properties of both categories. It has intermediate conductivity, making it useful in semiconductors.
• Nonmetals: Phosphorus (P), Sulfur (S), Chlorine (Cl), and Argon (Ar) lack the metallic luster and are poor conductors of electricity. They usually exist in different states compared to metals, especially under standard conditions.

Element appearance and color

Each element also varies in its appearance and color, which depends on its atomic structure and the type of light it reflects or emits. Here’s what you will observe among the third-period elements:

• Sodium (Na), Magnesium (Mg), and Aluminum (Al): These metals are silvery-white and have a metallic appearance.
• Silicon (Si): Known for its dark gray color with a bluish tint, Silicon possesses a metallic luster but is not shiny like metals.
• Phosphorus (P): Most commonly found in red form, displaying a nonmetallic appearance.
• Sulfur (S): Characterized by its yellow appearance, Sulfur is easy to identify amongst other elements.
• Chlorine (Cl): A pale yellow-green color in its gaseous form, making it easily distinguishable.
• Argon (Ar): Colorless gas, contributing to it being less visible in the atmosphere.

Standard states of elements

In chemistry, knowing an element's standard state is crucial as it describes their typical condition under standard temperature and pressure (STP). For the third-period elements, here's what you can expect at STP:

• Solid: Sodium (Na), Magnesium (Mg), Aluminum (Al), Silicon (Si), Phosphorus (P), and Sulfur (S) are all solid in standard conditions. Their atomic structures allow them to maintain rigidity and shape.
• Gas: Chlorine (Cl) and Argon (Ar) exist in gaseous form under standard conditions, indicating that their atoms are spaced out and move freely.

Understanding these states helps predict behaviors like reactivity and bonding capability in different conditions.