silver Symbol Ag. A white lustrous
soft metallic *transition element; a.n.
47; r.a.m. 107.87; r.d. 10.5; m.p.
961.93°C; b.p. 2212°C. It occurs as the
element and as the minerals argentite (Ag 2 S) and horn silver (AgCl). It is
also present in ores of lead and copper, and is extracted as a by-product
of smelting and reÜning these metals. The element is used in jewellery,
tableware, etc., and silver compounds are used in photography.
Chemically, silver is less reactive
than copper. A dark silver sulphide
forms when silver tarnishes in air because of the presence of sulphur
compounds. Silver(I) ionic salts exist
(e.g. AgNO 3 , AgCl) and there are a
number of silver(II) complexes.
A
• Information from the WebElements site
silver(I) bromide A yellowish
solid compound, AgBr; r.d. 6.5; m.p.
432°C. It can be precipitated from silver(I) nitrate solution by adding a solution containing bromide ions. It
dissolves in concentrated ammonia
solutions (but, unlike the chloride,
does not dissolve in dilute ammonia).
The compound is used in photographic emulsions.
silver(I) chloride A white solid
compound, AgCl; r.d. 5.6; m.p. 455°C;
b.p. 1550°C. It can be precipitated
from silver(I) nitrate solution by
adding a solution of chloride ions. It
dissolves in ammonia solution (due
to formation of the complex ion
[Ag(NH 3 ) 2 ]
+ ). The compound is used in
photographic emulsions.
silver(I) iodide A yellow solid
compound, AgI; r.d. 6.01; m.p. 558°C;
b.p. 1506°C. It can be precipitated
from silver(I) nitrate solutions by
adding a solution of iodide ions. Unlike the chloride and bromide, it does
not dissolve in ammonia solutions.
silver-mirror test See tollens
reagent.
silver(I) nitrate A colourless solid,
AgNO 3 ; r.d. 4.3; m.p. 212°C. It is an
important silver salt because it is
water-soluble. It is used in photography. In the laboratory, it is used as a
test for chloride, bromide, and iodide
ions and in volumetric analysis of
chlorides using an *adsorption indicator.
silver(I) oxide A brown slightly
water-soluble amorphous powder,
Ag 2 O; r.d. 7.14. It can be made by
adding sodium hydroxide solution to
silver(I) nitrate solution. Silver(I)
oxide is strongly basic and is also an
oxidizing agent. It is used in certain
reactions in preparative organic
chemistry; for example, moist
silver(I) oxide converts haloalkanes
into alcohols; dry silver oxide
converts haloalkanes into ethers.
The compound decomposes to
the elements at 300°C and can be
reduced by hydrogen to silver.
With ozone it gives the oxide AgO
(which is diamagnetic and probably
Ag
I Ag
III
O 2 ).
sima The rocks that form the
earth’s oceanic crust and underlie
the upper crust. These are basaltic
rock types rich in silica (SiO 2 ) and
magnesium (Mg), hence the name.
The sima is denser and more plastic
than the *sial that forms the continental crust.
Simmons–Smith reaction A reaction in which a cyclopropane ring is
produced form an alkene. It uses the
Simmons–Smith reagent, which was
originally diiodomethane (CH 2 I 2 )
with a Zn/Cu couple. Usually, diethyl
zinc is used rather than Zn/Cu. The
mechanism involves the formation of
H 2 C(I)(ZnI) and *carbene transfer
from the zinc to the double bond of
the alkene.
silver
484
s
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soft metallic *transition element; a.n.
47; r.a.m. 107.87; r.d. 10.5; m.p.
961.93°C; b.p. 2212°C. It occurs as the
element and as the minerals argentite (Ag 2 S) and horn silver (AgCl). It is
also present in ores of lead and copper, and is extracted as a by-product
of smelting and reÜning these metals. The element is used in jewellery,
tableware, etc., and silver compounds are used in photography.
Chemically, silver is less reactive
than copper. A dark silver sulphide
forms when silver tarnishes in air because of the presence of sulphur
compounds. Silver(I) ionic salts exist
(e.g. AgNO 3 , AgCl) and there are a
number of silver(II) complexes.
A
• Information from the WebElements site
silver(I) bromide A yellowish
solid compound, AgBr; r.d. 6.5; m.p.
432°C. It can be precipitated from silver(I) nitrate solution by adding a solution containing bromide ions. It
dissolves in concentrated ammonia
solutions (but, unlike the chloride,
does not dissolve in dilute ammonia).
The compound is used in photographic emulsions.
silver(I) chloride A white solid
compound, AgCl; r.d. 5.6; m.p. 455°C;
b.p. 1550°C. It can be precipitated
from silver(I) nitrate solution by
adding a solution of chloride ions. It
dissolves in ammonia solution (due
to formation of the complex ion
[Ag(NH 3 ) 2 ]
+ ). The compound is used in
photographic emulsions.
silver(I) iodide A yellow solid
compound, AgI; r.d. 6.01; m.p. 558°C;
b.p. 1506°C. It can be precipitated
from silver(I) nitrate solutions by
adding a solution of iodide ions. Unlike the chloride and bromide, it does
not dissolve in ammonia solutions.
silver-mirror test See tollens
reagent.
silver(I) nitrate A colourless solid,
AgNO 3 ; r.d. 4.3; m.p. 212°C. It is an
important silver salt because it is
water-soluble. It is used in photography. In the laboratory, it is used as a
test for chloride, bromide, and iodide
ions and in volumetric analysis of
chlorides using an *adsorption indicator.
silver(I) oxide A brown slightly
water-soluble amorphous powder,
Ag 2 O; r.d. 7.14. It can be made by
adding sodium hydroxide solution to
silver(I) nitrate solution. Silver(I)
oxide is strongly basic and is also an
oxidizing agent. It is used in certain
reactions in preparative organic
chemistry; for example, moist
silver(I) oxide converts haloalkanes
into alcohols; dry silver oxide
converts haloalkanes into ethers.
The compound decomposes to
the elements at 300°C and can be
reduced by hydrogen to silver.
With ozone it gives the oxide AgO
(which is diamagnetic and probably
Ag
I Ag
III
O 2 ).
sima The rocks that form the
earth’s oceanic crust and underlie
the upper crust. These are basaltic
rock types rich in silica (SiO 2 ) and
magnesium (Mg), hence the name.
The sima is denser and more plastic
than the *sial that forms the continental crust.
Simmons–Smith reaction A reaction in which a cyclopropane ring is
produced form an alkene. It uses the
Simmons–Smith reagent, which was
originally diiodomethane (CH 2 I 2 )
with a Zn/Cu couple. Usually, diethyl
zinc is used rather than Zn/Cu. The
mechanism involves the formation of
H 2 C(I)(ZnI) and *carbene transfer
from the zinc to the double bond of
the alkene.
silver
484
s
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