type of *bronze containing about 2%
beryllium, in addition to copper and
tin.
beryllium hydroxide A white
crystalline compound, Be(OH) 2 , precipitated from solutions of beryllium
salts by adding alkali. Like the oxide,
it is amphoteric and dissolves in excess alkali to give *beryllates.
beryllium oxide (beryllia) An insoluble solid compound, BeO; hexagonal; r.d. 3.01; m.p. 2530°C; b.p.
3900°C. It occurs naturally as bromellite, and can be made by burning
beryllium in oxygen or by the decomposition of beryllium carbonate
or hydroxide. It is an important amphoteric oxide, reacting with acids to
form salts and with alkalis to form
compounds known as *beryllates.
Beryllium oxide is used in the
production of beryllium and
beryllium–copper refractories, transistors, and integrated circuits.
Berzelius, Jöns Jacob (1779–1848)
Swedish chemist. After moving to
Stockholm he worked with mining
chemists and, with them, discovered
several elements, including cerium
(1803), selenium (1817), lithium
(1818), thorium (1828), and vanadium
(1830). He produced the Ürst accurate
table of atomic weights and was extremely inÛuential in the general
development of 19th-century
chemistry.
Bessemer process A process for
converting *pig iron from a *blast
furnace into *steel. The molten pig
iron is loaded into a refractory-lined
tilting furnace (Bessemer converter)
at about 1250°C. Air is blown into
the furnace from the base and
*spiegel is added to introduce the
correct amount of carbon. Impurities
(especially silicon, phosphorus, and
manganese) are removed by the converter lining to form a slag. Finally
the furnace is tilted so that the
molten steel can be poured off. In
the modern VLN (very low nitrogen)
version of this process, oxygen and
steam are blown into the furnace in
place of air to minimize the absorption of nitrogen from the air by the
steel. The process is named after the
British engineer Sir Henry Bessemer
(1813–98), who announced it in 1856.
See also basic-oxygen process.
beta decay A type of radioactive
decay in which an unstable atomic
nucleus changes into a nucleus of the
same mass number but different proton number. The change involves the
conversion of a neutron into a proton with the emission of an electron
and an antineutrino (n → p + e
– +
_
ν )
or of a proton into a neutron with
the emission of a positron and a neutrino (p → n + e
+ + ν). An example is
the decay of carbon–14:
14
6 C →
14
7 N + e
– +
_
ν
The electrons or positrons emitted
are called beta particles and streams
of beta particles are known as beta
radiation.
beta-iron A nonmagnetic allotrope
of iron that exists between 768°C
and 900°C.
beta particle See beta decay.
beta sheet (β-pleated sheet) A
form of secondary structure in *proteins in which extended polypeptide
chains lie parallel to each other and
are linked by hydrogen bonds between the N–H and C=O groups (see
illustration overleaf). Beta sheets
occur in many globular proteins and
link polypeptides of the same type in
certain Übrous proteins, including
Übroin (the protein of silk).
BET isotherm An isotherm that
takes account of the possibility that
the monolayer in the *Langmuir adsorption isotherm can act as a subberyllium hydroxide
66
b
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beryllium, in addition to copper and
tin.
beryllium hydroxide A white
crystalline compound, Be(OH) 2 , precipitated from solutions of beryllium
salts by adding alkali. Like the oxide,
it is amphoteric and dissolves in excess alkali to give *beryllates.
beryllium oxide (beryllia) An insoluble solid compound, BeO; hexagonal; r.d. 3.01; m.p. 2530°C; b.p.
3900°C. It occurs naturally as bromellite, and can be made by burning
beryllium in oxygen or by the decomposition of beryllium carbonate
or hydroxide. It is an important amphoteric oxide, reacting with acids to
form salts and with alkalis to form
compounds known as *beryllates.
Beryllium oxide is used in the
production of beryllium and
beryllium–copper refractories, transistors, and integrated circuits.
Berzelius, Jöns Jacob (1779–1848)
Swedish chemist. After moving to
Stockholm he worked with mining
chemists and, with them, discovered
several elements, including cerium
(1803), selenium (1817), lithium
(1818), thorium (1828), and vanadium
(1830). He produced the Ürst accurate
table of atomic weights and was extremely inÛuential in the general
development of 19th-century
chemistry.
Bessemer process A process for
converting *pig iron from a *blast
furnace into *steel. The molten pig
iron is loaded into a refractory-lined
tilting furnace (Bessemer converter)
at about 1250°C. Air is blown into
the furnace from the base and
*spiegel is added to introduce the
correct amount of carbon. Impurities
(especially silicon, phosphorus, and
manganese) are removed by the converter lining to form a slag. Finally
the furnace is tilted so that the
molten steel can be poured off. In
the modern VLN (very low nitrogen)
version of this process, oxygen and
steam are blown into the furnace in
place of air to minimize the absorption of nitrogen from the air by the
steel. The process is named after the
British engineer Sir Henry Bessemer
(1813–98), who announced it in 1856.
See also basic-oxygen process.
beta decay A type of radioactive
decay in which an unstable atomic
nucleus changes into a nucleus of the
same mass number but different proton number. The change involves the
conversion of a neutron into a proton with the emission of an electron
and an antineutrino (n → p + e
– +
_
ν )
or of a proton into a neutron with
the emission of a positron and a neutrino (p → n + e
+ + ν). An example is
the decay of carbon–14:
14
6 C →
14
7 N + e
– +
_
ν
The electrons or positrons emitted
are called beta particles and streams
of beta particles are known as beta
radiation.
beta-iron A nonmagnetic allotrope
of iron that exists between 768°C
and 900°C.
beta particle See beta decay.
beta sheet (β-pleated sheet) A
form of secondary structure in *proteins in which extended polypeptide
chains lie parallel to each other and
are linked by hydrogen bonds between the N–H and C=O groups (see
illustration overleaf). Beta sheets
occur in many globular proteins and
link polypeptides of the same type in
certain Übrous proteins, including
Übroin (the protein of silk).
BET isotherm An isotherm that
takes account of the possibility that
the monolayer in the *Langmuir adsorption isotherm can act as a subberyllium hydroxide
66
b
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