Metal bond is the bond between metals and metals. They form the so-called metal alloys, which are increasingly important to our daily lives.
In the solid state, metals are grouped in a geometrically ordered fashion, forming cells, or grids or crystalline reticulum. A metal sample consists of a large number of unit cells formed by cations of this metal.
In the bond between atoms of a metallic element, partial release of the outermost electrons occurs, with the consequent formation of cations, which form the unit cells. These cations have their charges stabilized by the released electrons that surround the structure like an electronic cloud. They are endowed with a certain movement and therefore called free electrons.
This free electron movement explains why metals are good electrical and thermal conductors. The consideration that electric current is a flow of electrons led to the creation of Electronic Cloud Theory or "Sea" theory of electrons.
The metal could be said to be a cluster of neutral atoms and cations, plunged into a cloud or "sea" of free electrons. This cloud of electrons would function as the metal bond that holds atoms together.
NaCl (sodium chloride) geometric figure
A 300-fold magnified crystal or crystal reticulum of NaCl
It is these bonds and their structures that metals have a number of very characteristic properties, such as metallic luster, electrical conductivity, high melting point, malleability, ductility, high density and tensile strength. .
Metal alloys are the union of two or more metals. Sometimes with nonmetals and metals. Alloys have more application than pure metals. Some leagues:
- bronze (copper + tin) - used in statues, bells.
- common steel (iron + 0.1 to 0.8% carbon) - with higher tensile strength, is used in construction, bridges, stoves, refrigerators.
- Stainless steel (iron + 0.1 carbon + 18% chrome + 8% nickel) - No rust (unlike iron and ordinary steel), is used in subway cars, stoves, sinks and cutlery.
- Brass (copper + zinc) - Used in guns and taps.
- gold / in jewelry (75% gold or silver + 25% copper) - used for jewelry making. 25% copper is used for 18K gold. And 24K gold is considered pure gold.
Metallic substances are represented graphically by the element symbol:
Example: Fe, Cu, Na, Ag, Au, Ca, Hg, Mg, Cs, Li.