Download Name: Beryllium Symbol: Be Atomic number:4 Mass

Kwun Tong Government Secondary School
Chemistry
Chu Hoi Ki 3B (4)
Name: Beryllium
Symbol: Be
Atomic number:4
Mass number:8
Number of protons:4
Number of neutrons:5
Number of electrons:4
Electronic arrangement:2,2
Period number:2
Group number:2 (Alkaline earth metal)
This sample is from The Elements Collection, an
attractive and safely packaged collection of the 92
naturally occurring elements that is available for sale.
Its chemistry is dominated by its tendency to lose an
electron to form Be2+. As this ion is so small it is highly
polarising, to the extent that its compounds are rather
covalent. Its small size means that its complexes tend
to be tetrahedral rahter than octahedral.
The mineral beryl, [Be3Al2(SiO3)6] is the most
important source of beryllium. It is roasted with sodimu
hexafluorosilicate, Na2SiF6, at 700°C to form beryllium
fluoride. This is water soluble and the beryllium may be
precipitated as the hydroxide Be(OH)2 by adjustment of
the pH to 12.Pure beryllium may be obtained by
electrolysis of molten BeCl2 containing some NaCl. The
salt is added since the molten BeCl2 conducts very
poorly. Another method involves the reduction of
beryllium fluoride with magnesium at 1300°C.
Beryllium is a relatively inert, hard, medium grey
metal, which is very light. It is nearly transparent for
X-rays. Beryllium is not often used, as it is quite
expensive and very toxic, in its elemental form as in
many of its compounds. However, it is an important
ingredient in many valuable gemstones, like beryl,
aquamarine and emerald. Clear beryl was used for
optical lenses in former times.