2.02 Properties of Metals and Nonmetals

Properties of Metals and Nonmetals

Conductivity

  • Metals: Conductors of heat and electricity.

  • Nonmetals: Insulators, generally do not conduct heat and electricity, but there are exceptions.

    • Exception: Carbon (graphite) conducts electricity.

    • Diamond conducts heat but not electricity.

Examples of Metals

  • Aluminum

  • Iron

  • Copper: Used in electrical wires due to its conductivity.

  • Silver: Very good conductor of electricity; used in wires.

  • Gold: Also a good conductor but expensive.

Examples of Nonmetals

  • Oxygen gas (O2): Present in the air we breathe (approximately 20%).

  • Nitrogen gas (N2): Makes up most of the atmospheric air (approximately 79%).

  • Chlorine (Cl2): Does not conduct electricity.

  • Helium (He): Used in balloons.

  • Sulfur (S):

Luster

  • Metals: Shiny with a metallic luster.

  • Nonmetals: Usually dull, lacking metallic luster.

Hardness and Malleability

  • Metals: Generally hard and do not break easily. Malleable (can be hammered into flat sheets) and ductile (can be drawn into wires).

  • Nonmetals: Usually brittle in solid form.

    • Exception: Alkaline metals (sodium, potassium) are soft and can be cut with a knife.

Reducing and Oxidizing Agents

  • Metals: Typically reducing agents, meaning they donate electrons.

    • Example:

      • Aluminum (Al) gives away three valence electrons to form Al^{3+} ions.

      • Iron (Fe) gives away two electrons to form Fe^{2+} ions.

    • Metals form positively charged ions called cations.

  • Nonmetals: Tend to be oxidizing agents, meaning they accept electrons.

    • Example:

      • Chlorine gas (Cl2) takes two electrons to form Cl^{-} ions.

      • Oxygen (O2) forms ions with a negative two charge, O^{2-}.

    • Nonmetals form negatively charged ions called anions.

Melting and Boiling Points

  • Metals: Generally have relatively high melting points and boiling points.

    • Example: Calcium (Ca) has a melting point of 842°C and a boiling point of 1484°C.

  • Nonmetals: Tend to have low melting and boiling points compared to metals.

    • Example: Oxygen (O2) has a melting point of -219°C and a boiling point of -183°C.

  • Exceptions and Specific Cases

    • Sodium (Na): Relatively low melting point of 98°C but a high boiling point of 883°C.

    • Sulfur (S): Melting point of 115°C, and a boiling point of 445°C. Higher melting point than Sodium.

    • Tungsten (W): Extremely high melting point of 3422°C and a boiling point of 5930°C.

    • Iodine (I): Solid at room temperature, with a melting point of 114°C and a boiling point of 184°C.

Molecular and Network Covalent Solids

  • Molecular Solids: Nonmetals that form molecular solids typically have low melting points and boiling points.

  • Network Covalent Solids: Nonmetals like graphite and diamond have extremely high melting points.

Exceptions

  • Gallium (Ga): A metal with a low melting point (30°C), it can melt in your hand. High boiling point.

  • Mercury (Hg): A liquid metal at room temperature.