Geoscience Reference
In-Depth Information
did not contain oxygen. Today, Cl 2 (g) is a product of
chemical reactions, primarily in the upper atmosphere.
into the air in soil dust and sea spray particles. Sodium
was isolated from caustic soda [sodium hydroxide,
NaOH(s)] by electrolysis. The name “sodium” derives
from the Italian word soda ,atermapplied to all alkalis
in the Middle Ages. Sodium is the sixth most abun-
dant element in the Earth's crust and is emitted in soil
dust and sea spray particles. Calcium was isolated from
quicklime [CaO(s)] by electrolysis. The name “cal-
cium” was derived from the word calx ,thename the
Romans used for lime. Calcium is the fifth most abun-
dant element in the Earth's crust and is emitted in soil
dust and sea spray particles.
In 1810, Davy also named the element chlorine ,pre-
viously called oxymuriatic acid. He proved that chlo-
rine was an element and that muriatic gas [HCl(g),
hydrochloric acid gas] contains chlorine and hydro-
gen, but no oxygen. He similarly proved that hydroflu-
oric acid gas [HF(g)] contains no oxygen. Both proofs
contradicted Lavoisier's theory that all acids contained
oxygen.
1.2.3. Discoveries after 1790
After 1790, the pace at which gas, liquid, and solid
chemicals were discovered increased. In the follow-
ing subsections, a few more chemicals of atmospheric
importance are discussed.
1.2.3.1. Elemental Potassium, Sodium, Calcium,
and Chlorine
In 1807/1808, Sir Humphry Davy (1778-1829; Figure
1.21), who along with Priestley is the most well-known
British chemist, developed electrolysis, which led to the
discovery of the elements potassium (K), sodium (Na),
calcium (Ca), and barium (Ba). Electrolysis is the pas-
sage of an electric current through a solution to break
down a compound or cause a reaction. Potassium was
isolated from caustic potash [potassium hydroxide,
KOH(s)] by electrolysis. Potassium is the seventh most
abundant element in the Earth's crust and is emitted
1.2.3.2. Elemental Silicon and Chemical Symbols
A contemporary of Davy, Jons Jakob Berzelius (1779-
1848) of Sweden discovered the elements silicon (Si)
(1823), selenium (Se) (1817), and thorium (Th) (1828).
He also spent ten years determining the atomic or
molecular weights of more than 2,000 elements and
compounds, publishing the results in 1818 and 1826.
Berzelius isolated silicon, a name derived from the Latin
word silex ,meaning “flint,” by fusing iron, carbon, and
the crystal quartz [SiO 2 (s)]. Silicon is the second most
abundant element in the Earth's crust, after oxygen, and
is present in soil dust particles.
Berzelius's most well-known achievement was to
invent a system of chemical symbols and notation. For
elements, he used the first one or two letters of the ele-
ment's Latin or Greek name. For example, oxygen was
denoted with an O, hydrogen with an H, mercury with
Hg (hydrargyrum), and lead with Pb (plumbum). For
compounds with more than one atom of an element, he
identified the number of atoms of the element with a
subscript. For example, he identified water with H 2 O.
1.2.3.3. Elemental Bromine and Hypochlorous
Acid (Gas)
In 1826, Antoine-Jerome Balard (1802-1876), a
French apothecary, accidentally discovered the ele-
ment bromine (Br) after analyzing the “bittern” (saline
liquor) that remained after common salt had crystal-
lized out of concentrated water in a salt marsh near
Figure 1.21. Sir Humphry Davy (1778-1829). Edgar
Fahs Smith Collection, University of Pennsylvania
Library.
 
Search WWH ::




Custom Search