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CHEMICAL BONDS
The Man Who
Saw Molecules
8.3.b Students know
that compounds are
formed by combining two or
more different elements and
that compounds have properties
that are different from their
constituent elements.
Linus Pauling was one of the great chemists of
the 20th century. He was a professor of chemistry at the California
Institute of Technology for 22 years. In 1939 he published a book
about chemical bonding. In it, Pauling showed that properties such as
the melting point or the boiling point of a substance depend on
molecular structure. He showed how chemical bonding influences a
molecule’s structure.
It’s in the Genes
Pauling discovered that oddly shaped
molecules could cause disease. For three
years, he researched a disease called sickle
cell anemia. A protein called hemoglobin carries oxygen through the blood.
Pauling found that in people with
sickle cell anemia, these molecules
have a different shape. In parts of
the bloodstream where there is
Normal red blood cells
low oxygen, these differently
are round. In sickle cell
shaped molecules cluster together.
anemia, red blood cells
This creates cells with long rod
are crescent shaped.
shapes resembling a sickle. It
becomes harder for the blood to
circulate. These molecules also don’t absorb oxygen, so
part of the body is starved of oxygen and iron. Pauling had
shown how a simple variation in molecular structure could
be very important.
Dangerous Chemistry
Pauling also studied how radiation affects humans.
He determined that radiation changes the chemistry
of the body. It damages human cells by changing
the shapes of molecules inside the body. The effects
of radiation could cause cancer and birth defects.
Pauling gave speeches around the world, arguing
against nuclear testing. Finally, in 1963 the United
States, the Soviet Union, and Great Britain signed
a limited test ban treaty. That year, Pauling was
awarded the Nobel Peace Prize. He is the only person
ever to receive two Nobel prizes as an individual.
WRITING ABOUT SCIENCE
Linus Pauling held that vitamin C could
prevent the common cold. Oranges are a
good source of vitamin C.
Find out more about Linus Pauling’s life and
work. Then write him a thank-you letter.
Describe one way his research improved your
life or the lives of other people.
Chapter 8: Chemical Bonds and Compounds 257
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