WHAT IS THIS?
THE CLAP SNAPPED
Seen in this photograph are Neisseria gonorrhoeae bacteria that
cause the infection gonorrhea, also known as ‘the clap’. The bacteria
are spread via contact with an infected person, most commonly
through sexual intercourse. Each bacterium measures between
0.6 and 1 micrometre. The hairlike appendages are called ‘fimbriae’
and they allow the bacteria to attach to surfaces.
DMITRI
MENDELEEVJOHN
NEWLANDSOn the wall of every school chemistry
laboratory is a poster of the periodic table
of elements. It has been the go-to
reference on chemical elements for
almost 150 years. Yet while the Russian
chemist Dmitri Mendeleev is often
credited with finding the rules behind
the block-like patterns of elements,
he was hardly alone: others had found
them some years before, but failed to
win recognition.
One of these scientists was John
Newlands, an English chemist who, in the
mid-1860s, pointed out that elements with
similar properties lie close together if
arranged according to their atomic mass.
But in describing his findings to fellow
scientists, he drew parallels with octaves
of musical notes, which prompted howls
of derision. Newlands’, discovery had in
any case been presaged by the work of
another English chemist, William Odling,
but he, too, failed to garner much interest.
Mendeleev’s claim to fame lies in
the fact that he realised that the patterns
were more complex than others had
realised, leading to some columns on the
table being longer than others. He also
suspected that gaps within the resulting
blocks implied the existence of as-yet
undiscovered elements, and bravely
attempted to predict their properties.
His confidence was vindicated with the
discovery of gallium, germanium and
scandium, ensuring his place among the
great names of 19th-century science. RMTHE PERIODIC TABLE
WHO REALLY INVENTED
February 2017 17