114
See also: Alessandro Volta 90–95 ■ Jöns Jakob Berzelius 119 ■
Hans Christian Ørsted 120 ■ Michael Faraday 121 ■ Dmitri Mendeleev 174–79I
n 1800, Alessandro Volta
invented the “voltaic pile”—
the world’s first battery, and
soon many other scientists began
to experiment with batteries.
English chemist Humphry Davy
realized that the battery’s electricity
is produced by a chemical reaction.
Electric charge flows as the pile’s
two different metals (the electrodes)
react via the brine-soaked paper
between them. In 1807, Davy found
that he could use the electric
charge from a pile to split chemical
compounds, discovering new
elements, and pioneering a process
that was later called electrolysis.New metals
Davy inserted two electrodes into
dry potassium hydroxide (potash),
which he moistened by exposing it
to the damp air in his laboratory so
that it would conduct electricity. To
his delight, metallic globules began
to form on the negatively charged
electrode. The globules were a new
element: the metal potassium. A
few weeks later, he electrolyzed
sodium hydroxide (caustic soda) inthe same way and produced the
metal sodium. In 1808, he used
electrolysis to discover four more
metallic elements—calcium, barium,
strontium, and magnesium—and
the metalloid boron. Like electrolysis,
their commercial use would prove
highly valuable. ■THE CHEMICAL
EFFECTS PRODUCED
BY ELECTRICITY
HUMPHRY DAVY (1778–1829)
IN CONTEXT
BRANCH
ChemistryBEFORE
1735 Swedish chemist
Georges Brandt discovers
cobalt, the first of many new
metallic elements to be found
over the next 100 years.1772 Italian physician Luigi
Galvani notices the effect
of electricity on a frog and
believes electricity is biological.1799 Alessandro Volta shows
that touching metals produce
electricity, and creates the
first battery.AFTER
1834 Davy’s former assistant
Michael Faraday publishes the
laws of electrolysis.1869 Dmitri Mendeleev
arranges the known elements
into a periodic table, creating a
group for the soft alkali metals
that Davy had been the first
to identify in 1807.Davy used apparatus similar to
this in his lectures at London’s Royal
Institution to show how electrolysis
splits water into its two elements,
hydrogen and oxygen.