Chemical Bonding - The Metallic Bond

Study Notes

Metallic bonding occurs between metal atoms.
Unlike ionic or covalent bonds, a positive and negative charge for identical atoms in a substance is difficult to explain.
Metal atoms have few valence electrons, making them unable to achieve a noble gas configuration through typical sharing or transferring of electrons.

Metal atoms give up their valence electrons, which then become delocalized.
These delocalized electrons form a "sea" around positively charged metal ions.
The positively charged metal ions are held together by the strong electrostatic attraction to this sea of delocalized electrons.

Metallic Shine: Metals typically have a grey color, although exceptions exist (gold, copper).
Physical State at Room Temperature (rtp): Most metals are solid at rtp, with mercury being an exception, which is liquid.
Good Conductivity of Heat and Electricity: The delocalized electrons can easily move and carry electrical charges. They also readily transfer kinetic energy, resulting in good heat conductivity.
High Melting Point, Great Hardness, and High Density: These properties result from the strong electrostatic forces between metal ions and delocalized electrons. Tungsten has the highest melting point among metals (3410°C), while osmium is exceptionally dense.
Malleability (Stretchable, Cuttable, Foldable): This property results from the ability of the metal atoms to slide past one another without disrupting the metallic bonds. In contrast, ionic compounds are brittle, as the disruption of the ionic lattice structure causes repulsion between like charges, leading to breakage.

An alloy is a mixture of one metal with another metal or a non-metal.
Alloys are created by replacing atoms with similar atomic radii, leading to a "solid solution" with new properties.
Examples of alloys include brass (copper and zinc), bronze (copper and tin), and stainless steel (iron, carbon, chromium, and nickel).
Introducing atoms with smaller atomic radii into a metal lattice prevents disruption of the metal lattice structure, hence strengthening the alloy. An example is steel (iron with carbon).

Question 31: Which is the best definition of metallic bonding?
Answer: The attraction between cations and delocalized electrons.
Question 32: What properties make aluminum suitable for baking foil, aircraft bodywork, cooking pans, and tent frames?
Answer: Malleability, thermal conductivity, and thermal stability (for various applications).