Chemistry Reference
In-Depth Information
bond, covalent
The chemical
bond
(link) between two
atoms
that share
electrons
.
bond, hydrogen
A chemical
bond
(link) resulting from the attraction between pos-
itively charged
hydrogen ions
and negatively charged
electrons
from other atoms,
such as those of oxygen.
bond, ionic
The
bond
(link) between two opposite charged
ions
resulting from the
attractive force between their electric charges.
bone
The rigid
composite material
that makes up the skeleton of vertebrate animals;
it consists of a mixture of
organic
matter, mainly
collagen
, impregnated with a
mineral
component, calcium carbonate phosphate.
bone ash
Calcinated bone
.
bone china
A type of
porcelain
made in Europe similar to Chinese porcelain, using
bone ash
as a
flux
.
borax
A
mineral
composed of
hydrated
sodium borate, also known as
tinkal
; it has
been used as a
flux
in
brazing
operations.
bp
Acronym for
basepair
; often used to express the length of
DNA
segments.
B
.
P
.
Acronym for
before present
;
radiocarbon
dates are, by convention, related to the
year 1950, which has been specified as “present.”
brass
An
alloy
consisting of copper (50-90%) and zinc (50-10%), in which small
amounts of other
elements,
such as lead, may also be present.
brazing
A
metallurgical
technique, also known as
hard soldering
, for permanently
joining together
metallic
parts using a
brazing alloy
.
brazing alloy
Generic name for
alloys
, also known as
hard or hot solders
, which are
used for joining
metals and alloys
at temperatures above 400°C and below the
melting point
of the
base metal
in the alloy.
brick
Small, generally rectangular block used for building
masonry
; in antiquity it
was made of a mixture of mud and straw, twigs, and/or dung that was either
dried (see
mud brick
) or fired (see
fired brick
).
brick, fired
Brick
fired to high temperature, generally above 600°C.
brick, mud
Brick
dried by exposure to the atmosphere and the heat of the sun.
brin
The common name used to refer to the two adjacent
filaments
of
silk
produced
by the silkworm.
brittleness
The property of
hard
and
rigid
solids to break without undergoing
deformation.
brocade
A firm, textured
textile
fabric with a complex design.
bronze
An
alloy
of copper (80-95%) and tin (20-5%) to which minor amounts of
other elements, such as zinc and lead, may have been added.
bronze disease
A particular form of the
corrosion
of
bronze
, very damaging to exca-
vated archaeological bronze objects, resulting from the interaction of chloride
ions
in bronze
patina
with moisture and oxygen in the air.
brown rot
See
rot, brown
.
buffing
The roughing, smoothing, or polishing of a surface with an
abrasive
or a
sharp tool.
