Dictionary of Chemistry [6th Ed.]

type of *bronze containing about 2%

beryllium, in addition to copper and

tin.

beryllium hydroxide A white

crystalline compound, Be(OH) 2 , pre-

cipitated from solutions of beryllium

salts by adding alkali. Like the oxide,

it is amphoteric and dissolves in ex-

cess alkali to give *beryllates.

beryllium oxide (beryllia)An in-

soluble solid compound, BeO; hexag-

onal; r.d. 3.01; m.p. 2530°C; b.p.

3900 °C. It occurs naturally as bromel-

lite, and can be made by burning

beryllium in oxygen or by the de-

composition of beryllium carbonate

or hydroxide. It is an important am-

photeric 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, tran-

sistors, 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 theÜrst accurate

table of atomic weights and was ex-

tremely 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 con-

verter 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 absorp-

tion 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 decayA type of radioactive

decay in which an unstable atomic

nucleus changes into a nucleus of the

same mass number but different pro-

ton number. The change involves the

conversion of a neutron into a pro-

ton 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 neu-

trino (p→n + e++ ν). An example is

the decay of carbon–14:

(^146) C → (^147) 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 particleSee beta decay.
beta sheet (β-pleated sheet)A
form of secondary structure in pro-
teins in which extended polypeptide
chains lie parallel to each other and
are linked by hydrogen bonds be-
tween 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
certainÜbrous proteins, including
Übroin (the protein of silk).
BET isothermAn isotherm that
takes account of the possibility that
the monolayer in the Langmuir ad-
sorption isotherm can act as a sub-
beryllium hydroxide 66
b