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Chlorine Facts
Chlorine Chemical
& Physical Properties
by Anne Marie
Helmenstine, Ph.D.
Atomic Number: 17
Symbol: Cl
Atomic Weight: 35.4527
Discovery: Carl
Wilhelm Scheele 1774 (Sweden)
Electron
Configuration: [Ne] 3s2 3p5
Word Origin: Greek: khloros: greenish-yellow
Properties: Chlorine
has a melting point of -100.98°C, boiling point of -34.6°C, density of 3.214
g/l, specific gravity of 1.56 (-33.6°C), with a valence
of 1, 3, 5, or 7.
Chlorine is a member of the halogen group
of elements and directly combines with almost all of the other elements.
.
Chlorine gas is a greenish yellow. Chlorine figures prominently in many organic chemistry reactions, particularly in substitutions with hydrogen.
.
Chlorine gas is a greenish yellow. Chlorine figures prominently in many organic chemistry reactions, particularly in substitutions with hydrogen.
The gas acts as an irritant for respiratory and other mucous
membranes.
The liquid form will burn the skin.
Humans can smell as low an amount as 3.5 ppm. A few breaths at a
concentration of 1000 ppm is usually fatal.
Uses: Chlorine
is used in many everyday products.
It is used for disinfecting drinking water.
Chlorine is used in the production of textiles, paper products,
dyes, petroleum products, medicines, insecticides, disinfectants, foods,
solvents, plastics, paints, and many other products.
The element is used to manufacture chlorates, carbon
tetrachloride, chloroform, and in the extraction of bromine.
Chlorine has been used as a chemical
warfare agent.
Sources: In
nature, chlorine is only found in the combined state, most commonly with sodium
as NaCl and in carnallite (KMgCl3•6H2O) and
sylvite (KCl).
The element is obtained
from chlorides by electrolysis or via the action of oxidizing agents.
Element Classification: Halogen
Chlorine Physical Data
Density (g/cc): 1.56 (@ -33.6 °C)
Melting Point (K): 172.2
Boiling Point (K): 238.6
Appearance: greenish-yellow,
irritating gas. At high pressure or low temperature: red to clear.
Isotopes: 16
known isotopes with
atomic masses ranging from 31 to 46 amu. Cl-35 and Cl-37 are
both stable isotopes with Cl-35 as the most abundant form (75.8%).
Atomic Volume (cc/mol): 18.7
Covalent Radius (pm): 99
Ionic Radius: 27
(+7e) 181 (-1e)
Specific Heat (@20°C
J/g mol): 0.477 (Cl-Cl)
Fusion Heat (kJ/mol): 6.41
(Cl-Cl)
Evaporation Heat (kJ/mol): 20.41 (Cl-Cl)
Pauling Negativity Number: 3.16
First Ionizing Energy (kJ/mol): 1254.9
Oxidation States: 7,
5, 3, 1, -1
Lattice Structure: Orthorhombic
Lattice Constant (Å): 6.240
CAS Registry
Number: 7782-50-5
Interesting Trivia:
· Chlorine leaks in containers are detected using ammonia.
Ammonia will react with the chlorine and form a white mist above the leak.
· The most common natural chlorine compound on Earth is sodium chloride
or table salt.
· Chlorine is the 21st most abundant element
in the Earth's crust
· Chlorine is the third most abundant element in the Earth's
oceans
· Chlorine gas was used as a chemical weapon during World War I.
Chlorine is heavier than air and would form a deadly layer in low-lying
foxholes and trenches.
Anne
Marie Helmenstine, Ph.D.
Introduction
Ph.D. in
biomedical sciences from the University of Tennessee at Knoxville - Oak Ridge
National Laboratory.
Science
educator with experience teaching chemistry, biology, astronomy, and
physics at the high school, college, and graduate levels.
ThoughtCo
and About Education chemistry expert since 2001.
Widely-published
graphic artist, responsible for printable periodic tables and other
illustrations used in science.
Experience
Anne
Helmenstine, Ph.D. has covered chemistry for ThoughtCo and About Education
since 2001, and other sciences since 2013. She taught chemistry, biology,
astronomy, and physics at the high school, college, and graduate levels.
She has worked as a research scientist and also abstracting and indexing
diverse scientific literature for the Department of Energy.
In
addition to her work as a science writer, Dr. Helmenstine currently serves as a
scientific consultant, specializing in problems requiring an interdisciplinary
approach. Previously, she worked as a research scientist and college
professor.
Education
Dr.
Helmenstine holds a Ph.D. in biomedical sciences from the University of
Tennessee at Knoxville and a B.A. in physics and mathematics with a minor
in chemistry from Hastings College. In her doctoral work, Dr. Helmenstine
developed ultra-sensitive chemical detection and medical diagnostic tests.
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