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Elements of groups 1 ... 10 of Periodic Table, elements of higher periods, groups 13,14,15are metals.
Metals are made up of atoms, containing a small number of electrons on the latest electronic layer. Because of this structure, metal atoms have low ionization energy and low electron affinity, ie metal atoms are characterized by relatively low levels of electro negativity. Chemical behavior of metallic atoms is characterized by tendency to give electrons (to oxidize) and turning into metal cations,showing reducing behavior :Mo – ze-oxidizing reaction-> Mz+
The ability of metal atoms to become ions is different and is expressed as the standard oxidation potential value, Eox0. In the table is usually given standard reduction potential of metal that is equal and opposite sign with the standard oxidation potential. After the standard potential value,metals can be classified in common metals and noble metals.
Oxygen is forming in reaction with metals,corresponding oxides:
2Zn + O2 = ZnO
Iron combination with oxygen form bi and trivalent combinations. The phenomenon of oxidation of iron is called rust.
Ferrous oxide, FeO (II), is obtained by direct combustion of iron. It is stable only at temperatures above 833 K (560oC) and is black.
Ferric oxide, Fe2O3 (III), also known as bloodstone, is a brown mineral , obtained by oxidation of iron to the existence of a surplus of oxygen. He is the main source for obtaining iron.
Ferric-ferrous oxide, Fe3O4 (II, III), known as magnetite, is a natural material with the best magnetic properties.
It oxidizes easily in air, forming oxides, and also in the presence of sulfur, with which form sulphides.
Although it is easily oxidised, the oxide layer is not sticky, so that for many years was the main metal used as connector. However, with technological progress in recent years, connectors of high quality are made of gold or plated silver.
Zinc is obtained from ores and compounds, is used in alloys with other metals to protect them against oxidation (rust).
Zinc is not considered toxic, however if inhaling zinc oxide (ZnO)appears a disorder known as "shaky zinc".
Metals react with oxygen by oxidation state to form basic oxides or amphoteric oxides.
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