Discovery of Radioactive
Elements
| As you have learned, Bequerel gave insight to a new form of energy,
radiation. His discovery inspired and excited many physcists at the time,
one of them was a remarkable female named Marie Curie. After hearing about
Bequerel's discovery she wondered if uranium was the only chemical that
had this strange property of radiating or was there others. With her husband,
Marie began what became their life long study of radioactivity. This new
topic required diligent and dedicated work, Marie Curie wrote, "The subject
seemed to us very attractive and all the more so because the question was
entirely new and nothing yet had been written upon it." |
Marie Curie |
Marie soon discovered that a rare element called thorium also produced
radiation. The work of the Curies had changed radiation from just a property
of uranium to a general property that some atoms possessed. Marie created
the term radioactivity to describe the phenomenon.
Further experiments that two uranium ores (unprocessed) were different
in properties. She extracted all the uranium out of one of the ores called
pitchblende but even after all the uranium had been extracted, the remaining
product was four times more radioactive than the extracted uranium itself.
She realized that the must be another undiscovered element in the remaining
ore - even more radioactive than uranium.
After further grinding, sifting and applying chemicals, they separated
out the radioactive material from the rest of the ore and found a compound
of sulfur and bismuth. Ordinary bismuth wasn't radioactive so there must
have been a substance mixed with it. Marie named the substance Polonium
after her home country. Even further, the liquid left over after the bismuth
and polonium had been filtered was still radioactive. The only known element
in the liquid was barium which like bismuth was nonradioactive. Just as
bismuth had a chemical cousin, polonium, the barium, too, must have a radioactive
cousin. Marie named the element Radium.
So far Marie had identified the two new materials through indirect means.
She needed to convince the community that these substances were real and
to do this she would need to isolate and purify enough so tests could be
made. These tests would determine the different properties and weights
of the new elements.
The work of Marie and Pierre Curie had shown that radioactivity was
a natural property. Two new elements, Polonium and Radium and had been
discovered and added to the periodic table. But probably the most important
achievement was the realization that radiation is an atomic property rather
than a separate emanation.
Despite the giant leap forward scientists still did no much about the
internal structure inside these atoms.This work was awaited for Ernest
Rutherford...
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