119
See also: Isaac Newton 62–69 ■ Alessandro Volta 90–95 ■ Joseph Proust 105 ■
Humphry Davy 114 ■ August Kekulé 160–65 ■ Linus Pauling 254–59T
he leading light of a
generation of chemists
inspired by Alessandro
Volta’s creation of the battery,
Sweden’s Jöns Jakob Berzelius
conducted a series of experiments
looking at the effect of electricity on
chemicals. He developed a theory
called electrochemical dualism,
published in 1819, which proposed
that compounds are created by the
coming together of elements with
opposite electrical charges.In 1803, Berzelius had teamed
up with a mine owner to make a
voltaic pile and see how electricity
splits salts. Alkali metals and
alkaline earths migrated to the
pile’s negative pole, while oxygen,
acids, and oxidized substances
migrated to the positive pole.
He concluded that salt compounds
combine a basic oxide, which is
positively charged, and an acidic
oxide, which is negatively charged.
Berzelius developed his
dualistic theory to suggest that
compounds are bonded by the
attraction of opposite electrical
charges between their constituent
parts. Though later shown to be
incorrect, the theory triggered
further research into chemical
bonds. In 1916, it was found that
electrical bonding occurs as “ionic”
bonding, in which atoms lose or
gain electrons to become mutually
attractive charged atoms, or ions.
In fact, this is just one of several
ways in which the atoms in a
compound bind—another is the
“covalent” bond, in which electrons
are shared between atoms. ■A CENTURY OF PROGRESS
EVERY CHEMICAL
COMPOUND HAS
TWO PARTS
JÖNS JAKOB BERZELIUS (1779–1848)
IN CONTEXT
BRANCH
Chemistry
BEFORE
1704 Isaac Newton suggests
that atoms are bonded by
some force.
1800 Alessandro Volta shows
that placing two different
metals next to each other can
produce electricity, and so
creates the first battery.
1807 Humphry Davy discovers
sodium and other metal
elements by splitting salts
with electrolysis.
AFTER
1857–58 August Kekulé
and others develop the idea
of valency—the number of
bonds an atom can form.
1916 US chemist Gilbert
Lewis proposes the idea of
the covalent bond in which
electrons are shared, while
German physicist Walther
Kossel suggests the idea
of ionic bonds.
The habit of an opinion
often leads to the complete
conviction of its truth, and
makes us incapable of
accepting the proofs against it.
Jöns Jakob Berzelius