Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Metal shopping experience:
1. Compare - without doubt the biggest advantage that the Metal offers shoppers today is the ability to compare thousands of Metal at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Metal? Wrong! If the Metal is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Metal then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Metal? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Metal and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Metal wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Metal then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Metal site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Metal, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Metal, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
.
In chemistry, a
metal (
Greek language:
fudgeon) fudgean chemical element that readily loses electrons to form positive
ions (cations) and has metallic bonds between metal atoms. Metals form
ionic bonds with non-metals. They are sometimes described as a
Crystal structure of positive ions surrounded by a cloud of delocalized
electrons. The metals are one of the three groups of elements as distinguished by their ionization and bonding properties, along with the
metalloids and
nonmetals. On the
Periodic table (metals and non-metals), a diagonal line drawn from boron (B) to
polonium (Po) separates the metals from the nonmetals. Most elements on this line are metalloids, sometimes called Semimetal; elements to the lower left are metals; elements to the upper right are nonmetals.
An alternative definition of metals is that they have overlapping conduction bands and
valence bands in their electronic structure. This definition opens up the category for metallic polymers and other organic metals, which have been made by researchers and employed in high-tech devices. These synthetic materials often have the characteristic silvery-grey reflectiveness (luster) of elemental metals.
The traditional definition focuses on the bulk properties of metals. They tend to be lustrous, ductile, malleable, and good Electrical conductors of electricity, while nonmetals are generally brittle (if solid), lack luster, and are Electrical insulations.
Chemical properties
Most metals are chemically reactive, reacting with oxygen in the air to form oxides over changing timescales (for example iron rusts over years and
potassium burns in seconds). The alkali metals react quickest followed by the
alkaline earth metals, found in the leftmost two groups of the periodic table. The
transition metals take much longer to oxidize (such as iron,
copper, zinc, nickel). 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, some
steels, and
titanium). The
oxides of metals are
Base (chemistry) (as opposed to those of nonmetals, which are acidic), although this may be considered a rule of thumb, rather than a fact.
Painting or
anodising metals are good ways to prevent their
corrosion. However, a more reactive metal in the
electrochemical series must be chosen for coating, especially when chipping of the coating is expected. Water and the two metals form an electrochemical cell, and if the coating is less reactive than the coatee, the coating actually
promotes corrosion.
Physical properties
Traditionally, metals have certain characteristic physical properties: they are usually shiny (they have
metallic Lustre (mineralogy)), have a high density, are ductile and malleable, usually have a high
melting point, are usually hard, are usually a solid at room temperature and conduct electricity,
heat and
sound well. However, this is mainly because the low density, soft, low melting point metals (the alkali metals and
alkaline earth metals) happen to be reactive, and we rarely encounter them in their elemental, metallic form.
The electrical and thermal conductivity of metals originate from the fact that in the metallic bond the outer electrons of the metal atoms form a gas of nearly free electrons, moving as an electron gas in a background of positive charge formed by the
ion cores. Good mathematical predictions for electrical conductivity, as well as the electrons' contribution to the heat capacity and heat conductivity of metals can be calculated from the
free electron model, which does not take the detailed structure of the ion lattice into account.
When considering the exact band structure and binding energy of a metal, it is necessary to take into account the positive potential caused by the specific arrangement of the ion cores - which is periodic in crystals. The most important consequence of the periodic potential is the formation of a small band gap at the boundary of the
brillouin zone. Mathematically, the potential of the ion cores is treated in the
nearly-free electron model.
Alloys
An alloy is a mixture of two or more
chemical element in solid solution in which the major component is a metal. Most pure metals are either too soft, brittle or chemically reactive for practical use. Combining different ratios of metals as alloys modify the properties of pure metals to produce desirable characteristics. The aim of making alloys is generally to make them less brittle, harder, resistant to corrosion, or have a more desirable color and luster. Examples of alloys are
steel (iron and
carbon),
brass (copper and
zinc), bronze (
copper and tin), and duralumin (aluminium and
copper). Alloys specially designed for highly demanding applications, such as
jet engines, may contain more than ten elements.
Categories
Base metal
In
chemistry, the term
'base metal' is used informally to refer to a metal that
oxidation or
corrosion relatively easily, and reacts variably with dilute hydrochloric acid (HCl) to form hydrogen. Examples include iron,
nickel, lead and zinc.
Copper is considered a base metal as it oxidizes relatively easily, although it does not react with HCl. It is commonly used in opposition to
noble metal.
In
alchemy, a
base metal was a common and inexpensive metal, as opposed to
precious metals, mainly gold and
silver. A longtime goal of the alchemists was the transmutation of base metals into precious metals.
In
numismatics, coins used to derive their value primarily from the
precious metal content. Most modern currencies are
fiat currency, allowing the coins to be made of
base metal.
Ferrous metal
The term "ferrous" is derived from the
Latin language meaning "containing iron". This can include pure iron, such as wrought iron, or an alloy such as steel. Ferrous metals are often magnetism, but not exclusively.
Noble metal
Noble metals are metals that are resistant to corrosion or
oxidation, unlike most
base metals. They tend to be precious metals, often due to perceived rarity. Examples include tantalum, gold,
platinum, and
rhodium.
Precious metal
A
precious metal is a rare metallic chemical element of high economic value.
Chemically, the precious metals are less reactivity than most elements, have high
Lustre (mineralogy) and high electrical conductivity. Historically, precious metals were important as
currency, but are now regarded mainly as investment and industrial commodity. Gold, silver, platinum and palladium each have an ISO 4217 currency code. The best-known precious metals are gold and silver. While both have industrial uses, they are better known for their uses in
art, jewelry, and currency. Other precious metals include the
Platinum group metals:
ruthenium, rhodium, palladium, osmium,
iridium, and
platinum, of which platinum is the most widely traded. Plutonium and
uranium could also be considered precious metals.
The demand for precious metals is driven not only by their practical use, but also by their role as investments and a
store of value. Palladium was, as of summer 2006, valued at a little under half the price of gold, and platinum at around twice that of gold. Silver is substantially less expensive than these metals, but is often traditionally considered a precious metal for its role in coinage and jewelry.
Extraction
Metals are often extracted from the Earth by means of mining, resulting in ores that are relatively rich sources of the requisite elements. Ore is located by
prospecting techniques, followed by the exploration and examination of deposits. Mineral sources are generally divided into
Surface mining, which are mined by excavation using heavy equipment, and
sub-surface mining.
Once the ore is mined, the metals must be
Extractive metallurgy, usually by chemical or electrolytic reduction. Pyrometallurgy uses high temperatures to convert ore into raw metals, while hydrometallurgy employs aqueous chemistry for the same purpose. The methods used depend on the metal and their contaminants.
Metallurgy
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys.
Applications
Some metals and metal alloys possess high structural strength per unit mass, making them useful materials for carrying large loads or resisting impact damage. Metal alloys can be engineered to have high resistance to shear, torque and deformation. However the same metal can also be vulnerable to fatigue damage through repeated use, or from sudden stress failure when a load capacity is exceeded. 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 appliances, tools, pipes, non-illuminated signs and railroad tracks.
Metals are good conductors, making them valuable in electrical appliances and for carrying an electric current over a distance with little energy lost. Electrical power grids rely on metal cables to distribute electricity. Home electrical systems, for the most part, are wired with copper wire for its good conducting properties.
The thermal conductivity of metal is useful for containers to heat materials over a flame. Metal is also used for heat sinks to protect sensitive equipment from overheating.
The high reflectivity of some metals is important in the construction of mirrors, including precision astronomical instruments. This last property can also make metallic jewelry aesthetically appealing.
Some metals have specialized uses; Radioactive metals such as
Uranium and
Plutonium are used in Nuclear reactor technology to produce energy via
nuclear fission. Mercury is a liquid at room temperature and is used in switches to complete a circuit when it flows over the switch contacts. Shape memory alloy is used for applications such as pipes, fasteners and vascular
stents. However they are very good at conducting electricity and heat.
Trade
imports in 2005The
World Bank reports that China was the top importer of ores and metals in 2005 followed by the U.S.A. and Japan.
Astronomy
In the specialised usage of astronomy and astrophysics, the term "metal" is often used to refer to any element other than hydrogen or
helium, and includes substances as chemically non-metallic as
neon,
fluorine, and oxygen. Because the temperatures of stellar bodies allow practically no solid or liquid matter, and little normal chemistry can exist at temperatures that break down almost all chemical bonds, the term "metal" refers to materials that result from the triple-helium process which are much scarcer than hydrogen and helium in stars in the main sequence.
See also
External links
- Live metal prices - USD/lb
.
In chemistry, a
metal (Greek language:
fudgeon) fudgean chemical element that readily loses electrons to form positive
ions (cations) and has metallic bonds between metal atoms. Metals form ionic bonds with non-metals. They are sometimes described as a
Crystal structure of positive ions surrounded by a cloud of delocalized
electrons. The metals are one of the three groups of elements as distinguished by their ionization and bonding properties, along with the metalloids and nonmetals. On the
Periodic table (metals and non-metals), a diagonal line drawn from
boron (B) to
polonium (Po) separates the metals from the nonmetals. Most elements on this line are metalloids, sometimes called
Semimetal; elements to the lower left are metals; elements to the upper right are nonmetals.
An alternative definition of metals is that they have overlapping conduction bands and valence bands in their electronic structure. This definition opens up the category for metallic polymers and other organic metals, which have been made by researchers and employed in high-tech devices. These synthetic materials often have the characteristic silvery-grey reflectiveness (luster) of elemental metals.
The traditional definition focuses on the bulk properties of metals. They tend to be lustrous, ductile, malleable, and good
Electrical conductors of electricity, while nonmetals are generally brittle (if solid), lack luster, and are Electrical insulations.
Chemical properties
Most metals are chemically reactive, reacting with oxygen in the air to form oxides over changing timescales (for example iron rusts over years and potassium burns in seconds). The alkali metals react quickest followed by the alkaline earth metals, found in the leftmost two groups of the
periodic table. The transition metals take much longer to oxidize (such as
iron,
copper,
zinc,
nickel). 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, some steels, and
titanium). The
oxides of metals are Base (chemistry) (as opposed to those of nonmetals, which are
acidic), although this may be considered a rule of thumb, rather than a fact.
Painting or
anodising metals are good ways to prevent their
corrosion. However, a more reactive metal in the
electrochemical series must be chosen for coating, especially when chipping of the coating is expected. Water and the two metals form an
electrochemical cell, and if the coating is less reactive than the coatee, the coating actually
promotes corrosion.
Physical properties
Traditionally, metals have certain characteristic physical properties: they are usually shiny (they have
metallic Lustre (mineralogy)), have a high
density, are
ductile and malleable, usually have a high
melting point, are usually hard, are usually a solid at room temperature and conduct electricity, heat and sound well. However, this is mainly because the low density, soft, low melting point metals (the
alkali metals and
alkaline earth metals) happen to be reactive, and we rarely encounter them in their elemental, metallic form.
The electrical and thermal conductivity of metals originate from the fact that in the
metallic bond the outer electrons of the metal atoms form a gas of nearly free electrons, moving as an electron gas in a background of positive charge formed by the ion cores. Good mathematical predictions for electrical conductivity, as well as the electrons' contribution to the heat capacity and heat conductivity of metals can be calculated from the
free electron model, which does not take the detailed structure of the ion lattice into account.
When considering the exact band structure and binding energy of a metal, it is necessary to take into account the positive potential caused by the specific arrangement of the ion cores - which is periodic in
crystals. The most important consequence of the periodic potential is the formation of a small band gap at the boundary of the
brillouin zone. Mathematically, the potential of the ion cores is treated in the
nearly-free electron model.
Alloys
An alloy is a mixture of two or more
chemical element in solid solution in which the major component is a metal. Most pure metals are either too soft, brittle or chemically reactive for practical use. Combining different ratios of metals as alloys modify the properties of pure metals to produce desirable characteristics. The aim of making alloys is generally to make them less brittle, harder, resistant to corrosion, or have a more desirable color and luster. Examples of alloys are
steel (
iron and carbon), brass (copper and
zinc), bronze (
copper and tin), and
duralumin (aluminium and copper). Alloys specially designed for highly demanding applications, such as
jet engines, may contain more than ten elements.
Categories
Base metal
In chemistry, the term
'base metal' is used informally to refer to a metal that oxidation or
corrosion relatively easily, and reacts variably with dilute
hydrochloric acid (HCl) to form hydrogen. Examples include
iron,
nickel, lead and
zinc.
Copper is considered a base metal as it oxidizes relatively easily, although it does not react with HCl. It is commonly used in opposition to noble metal.
In alchemy, a
base metal was a common and inexpensive metal, as opposed to
precious metals, mainly
gold and
silver. A longtime goal of the alchemists was the transmutation of base metals into precious metals.
In numismatics, coins used to derive their value primarily from the precious metal content. Most modern currencies are fiat currency, allowing the coins to be made of
base metal.
Ferrous metal
The term "ferrous" is derived from the
Latin language meaning "containing iron". This can include pure iron, such as wrought iron, or an alloy such as steel. Ferrous metals are often magnetism, but not exclusively.
Noble metal
Noble metals are metals that are resistant to corrosion or oxidation, unlike most base metals. They tend to be precious metals, often due to perceived rarity. Examples include
tantalum,
gold, platinum, and rhodium.
Precious metal
A
precious metal is a rare metallic
chemical element of high
economic value.
Chemically, the precious metals are less
reactivity than most elements, have high
Lustre (mineralogy) and high electrical conductivity. Historically, precious metals were important as
currency, but are now regarded mainly as investment and industrial commodity. Gold, silver, platinum and palladium each have an
ISO 4217 currency code. The best-known precious metals are gold and silver. While both have industrial uses, they are better known for their uses in
art,
jewelry, and
currency. Other precious metals include the Platinum group metals: ruthenium,
rhodium,
palladium,
osmium, iridium, and
platinum, of which platinum is the most widely traded.
Plutonium and uranium could also be considered precious metals.
The demand for precious metals is driven not only by their practical use, but also by their role as investments and a
store of value. Palladium was, as of summer 2006, valued at a little under half the price of gold, and platinum at around twice that of gold. Silver is substantially less expensive than these metals, but is often traditionally considered a precious metal for its role in coinage and jewelry.
Extraction
Metals are often extracted from the Earth by means of mining, resulting in ores that are relatively rich sources of the requisite elements. Ore is located by
prospecting techniques, followed by the exploration and examination of deposits. Mineral sources are generally divided into Surface mining, which are mined by excavation using heavy equipment, and sub-surface mining.
Once the ore is mined, the metals must be
Extractive metallurgy, usually by chemical or electrolytic reduction.
Pyrometallurgy uses high temperatures to convert ore into raw metals, while hydrometallurgy employs aqueous chemistry for the same purpose. The methods used depend on the metal and their contaminants.
Metallurgy
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys.
Applications
Some metals and metal alloys possess high structural strength per unit mass, making them useful materials for carrying large loads or resisting impact damage. Metal alloys can be engineered to have high resistance to shear, torque and deformation. However the same metal can also be vulnerable to fatigue damage through repeated use, or from sudden stress failure when a load capacity is exceeded. 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 appliances, tools, pipes, non-illuminated signs and railroad tracks.
Metals are good conductors, making them valuable in electrical appliances and for carrying an electric current over a distance with little energy lost. Electrical power grids rely on metal cables to distribute electricity. Home electrical systems, for the most part, are wired with copper wire for its good conducting properties.
The thermal conductivity of metal is useful for containers to heat materials over a flame. Metal is also used for
heat sinks to protect sensitive equipment from overheating.
The high reflectivity of some metals is important in the construction of mirrors, including precision astronomical instruments. This last property can also make metallic jewelry aesthetically appealing.
Some metals have specialized uses; Radioactive metals such as Uranium and
Plutonium are used in Nuclear reactor technology to produce energy via
nuclear fission. Mercury is a liquid at room temperature and is used in switches to complete a circuit when it flows over the switch contacts. Shape memory alloy is used for applications such as pipes, fasteners and vascular stents. However they are very good at conducting electricity and heat.
Trade
imports in 2005The World Bank reports that China was the top importer of ores and metals in 2005 followed by the U.S.A. and Japan.
Astronomy
In the specialised usage of astronomy and
astrophysics, the term "metal" is often used to refer to any element other than
hydrogen or
helium, and includes substances as chemically non-metallic as neon,
fluorine, and oxygen. Because the temperatures of stellar bodies allow practically no solid or liquid matter, and little normal chemistry can exist at temperatures that break down almost all chemical bonds, the term "metal" refers to materials that result from the triple-helium process which are much scarcer than hydrogen and helium in stars in the
main sequence.
See also
External links
- Live metal prices - USD/lb
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