about 10 metals and details
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A metal (from Greek μέταλλον métallon , "mine, quarry, metal" [1][2] ) is a material (an element ,
compound , or alloy ) that is typically hard when in
solid state, opaque, shiny, and has good electrical and thermal conductivity. Metals are generally
malleable —that is, they can be hammered or pressed permanently out of shape without breaking or cracking—as well as fusible (able to be fused or melted) and ductile (able to be drawn out into a thin wire). [3] Around 90 of the 118 elements in the
periodic table are metals; the others are nonmetals or metalloids , though elements near the boundaries of each category have been assigned variably to either (hence the lack of an exact count). Some elements appear in both metallic and non-metallic forms.
Astrophysicists use the term "metal" to refer collectively to all elements in a star that are heavier than the lightest two, hydrogen and helium , and not just traditional metals. A star fuses lighter atoms, mostly hydrogen and helium, to make heavier atoms over its lifetime. Used in that sense, the metallicity of an astronomical object is the proportion of its matter made up of the heavier chemical elements. [4]
Many elements and compounds that are not normally classified as metals become metallic under high pressures; these are formed as metallic allotropes of non-metals , for example, physicists were able to keep hydrogen in its solid state under more than 3 million times the atmospheric pressure and deduce its metallic properties. [5]
The strength and resilience of metals has led to their frequent use in high-rise building and bridge
construction , as well as most vehicles, many home appliances , tools, pipes, non-illuminated signs and railroad tracks. Precious metals were historically used as coinage .
In the periodic table
The elements which are considered as metals under ordinary conditions are shown in yellow on the periodic table below. The remaining elements are shown either as nonmetals or as metalloids of intermediate character.
v t e
1 2
Group →
↓ Period
1 H
2 Li Be
3 Na Mg
4 K Ca Sc
5 Rb Sr Y
6 Cs Ba La Ce Pr Nd Pm Sm Eu Gd
7 Fr Ra Ac Th Pa U Np Pu Am Cm
Un
Structure and bonding
Image
hcp and fcc close-packing of spheres
The atoms of metallic substances are typically arranged in one of three common crystal structures , namely body-centered cubic (bcc), face-centered cubic (fcc), and hexagonal close-packed (hcp). In bcc, each atom is positioned at the center of a cube of eight others. In fcc and hcp, each atom is surrounded by twelve others, but the stacking of the layers differs. Some metals adopt different structures depending on the temperature. [6]
Atoms of metals readily lose their outer shell electrons, resulting in a free flowing cloud of electrons within their otherwise solid arrangement. This provides the ability of metallic substances to easily transmit heat and electricity. While this flow of electrons occurs, the solid characteristic of the metal is produced by electrostatic interactions between each atom and the electron cloud. This type of bond is called a metallic bond. [7]
Crystal structures for some metals are listed in the table below
Metal Crystal Structure Atomic Number Atomic Radius (nm)
Aluminium FCC 13 0.1431
Cadmium HCP 48 0.1490
Chromium BCC 24 0.1249
Cobalt HCP 27 0.1253
Copper FCC 29 0.1278
Gold FCC 79 0.1442
Iron (α) BCC 26 0.1241
Lead FCC 82 0.1750
Molybdenum BCC 42 0.1363
Nickel FCC 28 0.1246
Platinum FCC 78 0.1387
Silver FCC 47 0.1445
Tantalum BCC 73 0.1430
Titanium (α) HCP 22 0.1445
Tungsten BCC 74 0.1371
Zinc HCP 30 0.1332
Properties
Chemical
Metals are usually inclined to form cations through electron loss, [7] reacting with oxygen in the air to form oxides over various timescales (iron rusts over years, while potassium burns in seconds). Examples:
4 Na + O2 → 2 Na2O (sodium oxide)
2 Ca + O2 → 2 CaO (calcium oxide)
4 Al + 3 O2 → 2 Al2O3 (aluminium oxide).
The transition metals (such as iron , copper , zinc , and nickel ) are slower to oxidize because they form a passivating layer of oxide that protects the interior. Others, like palladium , platinum and gold , do not react with the atmosphere at all. Some metals form a barrier layer of oxide on their surface which cannot be penetrated by further oxygen molecules and thus retain their shiny appearance and good conductivity for many decades (like aluminium , magnesium, some steels , and titanium). The oxides of metals are generally basic , as opposed to those of nonmetals , which are acidic . Exceptions are largely oxides with very high oxidation states such as CrO3, Mn2O7, and OsO4, which have strictly acidic reactions.
compound , or alloy ) that is typically hard when in
solid state, opaque, shiny, and has good electrical and thermal conductivity. Metals are generally
malleable —that is, they can be hammered or pressed permanently out of shape without breaking or cracking—as well as fusible (able to be fused or melted) and ductile (able to be drawn out into a thin wire). [3] Around 90 of the 118 elements in the
periodic table are metals; the others are nonmetals or metalloids , though elements near the boundaries of each category have been assigned variably to either (hence the lack of an exact count). Some elements appear in both metallic and non-metallic forms.
Astrophysicists use the term "metal" to refer collectively to all elements in a star that are heavier than the lightest two, hydrogen and helium , and not just traditional metals. A star fuses lighter atoms, mostly hydrogen and helium, to make heavier atoms over its lifetime. Used in that sense, the metallicity of an astronomical object is the proportion of its matter made up of the heavier chemical elements. [4]
Many elements and compounds that are not normally classified as metals become metallic under high pressures; these are formed as metallic allotropes of non-metals , for example, physicists were able to keep hydrogen in its solid state under more than 3 million times the atmospheric pressure and deduce its metallic properties. [5]
The strength and resilience of metals has led to their frequent use in high-rise building and bridge
construction , as well as most vehicles, many home appliances , tools, pipes, non-illuminated signs and railroad tracks. Precious metals were historically used as coinage .
In the periodic table
The elements which are considered as metals under ordinary conditions are shown in yellow on the periodic table below. The remaining elements are shown either as nonmetals or as metalloids of intermediate character.
v t e
1 2
Group →
↓ Period
1 H
2 Li Be
3 Na Mg
4 K Ca Sc
5 Rb Sr Y
6 Cs Ba La Ce Pr Nd Pm Sm Eu Gd
7 Fr Ra Ac Th Pa U Np Pu Am Cm
Un
Structure and bonding
Image
hcp and fcc close-packing of spheres
The atoms of metallic substances are typically arranged in one of three common crystal structures , namely body-centered cubic (bcc), face-centered cubic (fcc), and hexagonal close-packed (hcp). In bcc, each atom is positioned at the center of a cube of eight others. In fcc and hcp, each atom is surrounded by twelve others, but the stacking of the layers differs. Some metals adopt different structures depending on the temperature. [6]
Atoms of metals readily lose their outer shell electrons, resulting in a free flowing cloud of electrons within their otherwise solid arrangement. This provides the ability of metallic substances to easily transmit heat and electricity. While this flow of electrons occurs, the solid characteristic of the metal is produced by electrostatic interactions between each atom and the electron cloud. This type of bond is called a metallic bond. [7]
Crystal structures for some metals are listed in the table below
Metal Crystal Structure Atomic Number Atomic Radius (nm)
Aluminium FCC 13 0.1431
Cadmium HCP 48 0.1490
Chromium BCC 24 0.1249
Cobalt HCP 27 0.1253
Copper FCC 29 0.1278
Gold FCC 79 0.1442
Iron (α) BCC 26 0.1241
Lead FCC 82 0.1750
Molybdenum BCC 42 0.1363
Nickel FCC 28 0.1246
Platinum FCC 78 0.1387
Silver FCC 47 0.1445
Tantalum BCC 73 0.1430
Titanium (α) HCP 22 0.1445
Tungsten BCC 74 0.1371
Zinc HCP 30 0.1332
Properties
Chemical
Metals are usually inclined to form cations through electron loss, [7] reacting with oxygen in the air to form oxides over various timescales (iron rusts over years, while potassium burns in seconds). Examples:
4 Na + O2 → 2 Na2O (sodium oxide)
2 Ca + O2 → 2 CaO (calcium oxide)
4 Al + 3 O2 → 2 Al2O3 (aluminium oxide).
The transition metals (such as iron , copper , zinc , and nickel ) are slower to oxidize because they form a passivating layer of oxide that protects the interior. Others, like palladium , platinum and gold , do not react with the atmosphere at all. Some metals form a barrier layer of oxide on their surface which cannot be penetrated by further oxygen molecules and thus retain their shiny appearance and good conductivity for many decades (like aluminium , magnesium, some steels , and titanium). The oxides of metals are generally basic , as opposed to those of nonmetals , which are acidic . Exceptions are largely oxides with very high oxidation states such as CrO3, Mn2O7, and OsO4, which have strictly acidic reactions.
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