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Introduction Characteristics of Metals The Metallic Model The Structure of Metals: the Lattice Arrangement Metallic Bonding Conductors Malleability and Ductility Melting Points and Strength Metallic Luster Alloys and Modified Properties Energy and Strength of Metallic Bonds Metallic vs Ionic vs Covalent Bonding Applications Summary
Metals are the backbone of modern technology, from electrical wiring in cars to the materials used to build cars and houses. The properties that make metals useful, such as conductivity, malleability, strength, and luster, are all attributed to a special kind of bond called metallic bonding. The electron sea model, or the sea of electrons model, describes the reason for the different properties of metals compared to substances formed through covalent or ionic bonds.
It is important to understand how the concepts of delocalized electrons, lattice structure, bond strength, and metallic properties correlate.
The defining characteristics of metals include:
Copper, Iron, Aluminum, Gold, and Silver are common examples. These properties come from the structure and arrangement of the valence electrons in the metallic lattice.
Metals crystallize in regular three-dimensional lattices, typically in face-centered cubic (FCC), body-centered cubic (BCC), or hexagonal close-packed (HCP) structures.
Important elements include:
This repetition gives the strength, ductility, thermal, and electrical conductivity.
The structural lattice guarantees metals retain strength while adapting and flexibility, which separates them from brittle ionic crystals.
Metallic Bonding is a term that describes the electrostatic attraction between positive ions and delocalized electrons. What are some reasons for bond strength?
This is why magnesium (Mg) > sodium (Na) as Mg has more valence electrons that are available for the "sea of electrons."
Examples of heat and electric conductor applications are copper wiring, heating devices, electrical wiring, and devices that conduct heat.
Malleability means that metals can be flattened into sheets through the use of a hammer (the larger the number of cations present, the larger the elongation of that metal ion occurs).
The same electron sea that allows metals to be hammered into sheets also allows them to be drawn into wires, which is the definition of ductility, as well.
These characteristics of metals make them well utilized in the manufacture of sheets of metal, foils, and wires.
The temperature at which a metal melts, as well as the strength of that metal, is also a direct result of the strength of the bonds that exist in that metal.
Metals that have more free electrons and possess smaller and more positively charged cations will have a greater number of bonds and will have higher melting points as well.
Here are some examples of the melting points of various metallic elements and the reasons for them.
has weak metallic bonds, which means it has a low melting point of 98°C.
has stronger metallic bonds than sodium, which means it has a higher melting point of 660°C.
has extremely strong metallic bonds and therefore has an extremely high melting point of 3422°C.
Light interacts with the free-flowing electrons present in metals. They absorb and re-emit a photon, and this phenomenon is called metallic luster. They are used in making mirrors, decorative pieces, and jewelry.
Alloys can be defined as any combination of metals and metals with non-metals. Examples of alloys include:
Iron + Carbon: more durable than pure iron
Copper + Tin: more resistant to corrosion
Copper + Zinc: more durable and more malleable
Alloying mixes metals to increase the alloy's strength. This is done by making the metals of the mix have differently sized atoms. This leads to the formation of a lattice. This lattice will avoid the layer of the differently sized atoms from sliding too easily. This phenomenon is called disruption, and it increases the strength, hardness, and durability of the alloy. The more durable and corrosion-resistant the alloy is, the more it can be used in construction, machines, and electronics, especially in the aerospace sector.
The energy is defined by the following phenomenon:
The stronger the bonds of the elements involved, the higher the melting point, hardness, and durability.
| Property | Metallic | Ionic | Covalent |
|---|---|---|---|
| Electron behavior | Delocalized | Transferred | Shared |
| Electrical conductivity | Solid: good, Molten: good | Solid: poor, Molten: good | Poor, except delocalized |
| Structure | Lattice of ions | Ionic lattice | Molecules or giant lattice |
| Malleability | High | Brittle | Usually low |
| Bond strength | Moderate to high | Very high | Strong (within molecule) |
This comparison shows that bonding metals is different from bonding ionic crystals or covalent molecules, which is why they are conductive, malleable, and strong.
Applying the metallic model is crucial for engineering, materials science, and nanotechnology.
The limitations of the metallic bonding model provide a basis to connect the atomic structure to the properties of metals in practical applications, and make it an important model in Chemistry to appreciate the science, engineering, and technology of materials in the modern world.