Celebrating 22 Years on the Web
Find science on or your birthday


Stories About Chemistry


72. The Most Unusual Atom, the Most Unusual Chemistry

The symbol of this remarkable atom is Ps But in vain will you search Mendeleyev’s Table for it. It is not the atom of any chemical element

And its lifetime is only an instant, less than a ten-millionth of a second Still, it cannot be said to be radioactive.

Ps stands for positronium. Its structure is very simple.

Take a hydrogen atom, the simplest of all the atoms of chemical elements. One electron revolves about a single proton.

The positronium atom appears in certain types of radioactive transformations accompanied by the emission of a positron. For a very short time the positron forms a stable system with an electron.

In positronium the part of the proton is played by an elementary particle known as the positron. It is the antipode of the electron. The positron has the same size and the same mass as the electron, the difference being that its charge is of the opposite sign (positive).

A collision between a positron and an electron is the end of both of them. As the physicists put it, they annihilate each other. In other words, they turn into nothing, or to be more exact, into a radiation.

But just before disappearing these two unreconcilable enemies exist side by side for a short instant giving rise to the ghost positronium atom. It is an atom with no nucleus, for the electron and the positron revolve about a common centre of gravity.

Now who could be interested in positronium? Only theoretical physicists, it would seem; or maybe science-fiction writers searching for new types of fuel for their stellar spaceships.

But not long ago a thick book entitled “The Chemistry of Positronium” was published in the USA. This is no science fiction. The book was written by serious scientists and treats of how the investigators make this unusual atom serve their purposes.

During its brief lifetime, positronium is capable of entering into chemical reaction. It reacts especially readily with chemical compounds which have free valence bonds left. These unused vacancies are occupied by positronium atoms.

By means of special instruments chemists can trace the nature of decay of positronium which has got into the molecule of a substance. It is found to decay differently, depending on the structure of the molecule. This enables chemists to study the intricacies of molecular designs and to solve many sophisticated and controversial problems where other methods have failed.

< back     next >

- 100 -
Sophie Germain
Gertrude Elion
Ernest Rutherford
James Chadwick
Marcel Proust
William Harvey
Johann Goethe
John Keynes
Carl Gauss
Paul Feyerabend
- 90 -
Antoine Lavoisier
Lise Meitner
Charles Babbage
Ibn Khaldun
Ralph Emerson
Robert Bunsen
Frederick Banting
Andre Ampere
Winston Churchill
- 80 -
John Locke
Bronislaw Malinowski
Thomas Huxley
Alessandro Volta
Erwin Schrodinger
Wilhelm Roentgen
Louis Pasteur
Bertrand Russell
Jean Lamarck
- 70 -
Samuel Morse
John Wheeler
Nicolaus Copernicus
Robert Fulton
Pierre Laplace
Humphry Davy
Thomas Edison
Lord Kelvin
Theodore Roosevelt
Carolus Linnaeus
- 60 -
Francis Galton
Linus Pauling
Immanuel Kant
Martin Fischer
Robert Boyle
Karl Popper
Paul Dirac
James Watson
William Shakespeare
- 50 -
Stephen Hawking
Niels Bohr
Nikola Tesla
Rachel Carson
Max Planck
Henry Adams
Richard Dawkins
Werner Heisenberg
Alfred Wegener
John Dalton
- 40 -
Pierre Fermat
Edward Wilson
Johannes Kepler
Gustave Eiffel
Giordano Bruno
JJ Thomson
Thomas Kuhn
Leonardo DaVinci
David Hume
- 30 -
Andreas Vesalius
Rudolf Virchow
Richard Feynman
James Hutton
Alexander Fleming
Emile Durkheim
Benjamin Franklin
Robert Oppenheimer
Robert Hooke
Charles Kettering
- 20 -
Carl Sagan
James Maxwell
Marie Curie
Rene Descartes
Francis Crick
Michael Faraday
Srinivasa Ramanujan
Francis Bacon
Galileo Galilei
- 10 -
John Watson
Rosalind Franklin
Michio Kaku
Isaac Asimov
Charles Darwin
Sigmund Freud
Albert Einstein
Florence Nightingale
Isaac Newton

by Ian Ellis
who invites your feedback
Thank you for sharing.
Today in Science History
Sign up for Newsletter
with quiz, quotes and more.