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Metallic Bonding (Alloys (Example (Steel, Coin Metals, Brass, Bronze,…
Metallic Bonding
Structure
Sea Of Electrons
Metals have low ionization energy. Therefore, the valence electrons can be delocalized throughout the metals. Delocalized electrons are not associated with a particular nucleus of a metal, instead, they are free to move throughout the whole crystalline structure forming a "sea" of electrons.
Metals form giant structures in which electrons in the outer shells of the metal atoms are free to move. The metallic bond is the force of attraction between these free electrons and metal ions. Metallic bonds are strong, so metals can maintain a regular structure and usually have high melting and boiling points.
Bond
A metallic bond is the electrostatic attraction between a lattice of positive ions and delocalized electrons.
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Electrical Conductivity
Metals are good conductors of heat and electricity because of the mobile delocalized electrons. When a potential is applied to the metal, the mobile electrons can move through the metallic structure and hence carry an electric.
Malleability/ Hardness
Metals are malleable. Malleability is the ability of a solid to be pounded or hammered into a sheet or other shape without breaking. The reason why metals have this property is that the positive ions (cations) can slide past one another, which leads to a rearrangement of the shape of the solid.
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Melting Point
Metallic bonds are very strong therefore metals often have a high melting point. For example, Tungsten = 3414°C, although some have a very low melting point like Mercury has -38.8°C.
The melting point of a metal depends on the strength of the attractive forces that hold the positive ions within the "sea" of delocalized electrons. The melting point od calcium is higher than potassium.
Solubility
Metals are insoluble in water or organic solvents unless they undergo a reaction with them. Typically this is an oxidation reaction that robs the metal atoms of their itinerant electrons, destroying the metallic bonding.
Ductility
Metals are highly ductile as they can be stretched into thin wires, such as those used for electricity.
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Examples
All pure metals: Na, Fe, Al, Au, Ag...
Alloys
Example
Steel, Coin Metals, Brass, Bronze, Pewter
An alloy is a mixture of metals or a mixture of a metal and another element. Alloys are defined by a metallic bonding character. An alloy may be a solid solution of metal elements (a single phase) or a mixture of metallic phases (two or more solutions). Intermetallic compounds are alloys with a defined stoichiometry and crystal structure.
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