Marie Curie and The Atomic Theory

The Atomic Theory

• Atom Structure (Protons, Neutrons, Electrons)
• Atomic/Electron Configuration
• Atomic Mass
• Atomic Mass Number
• Atomic Number
• Atomic Orbital (Quantum)
• Atomic Theory of Matter 

Ninety years later, Pierre and Marie Curie were to discover and isolate radium, a new element which spontaneously disintegrated into other elements. This proved that the atoms of one element at least were not indivisible.

---

Marie Curie's Study: The Discovery of Radium and Polonium /Radioactivity
Who is Marie Curie?
A Polish born French Chemist, with her French born husband Pierre Curie (1859-1906), Marie Curie (1867-1934) worked on radioactivity and in 1898 she reported the possible existence of a new, powerfully radioactive element in pitch blend ores. Her husband abandoned his own researches to assist her and discovered the radioactive elements polonium and radium in the pure state in 1902.
They both refused to take out a patient on their discoveries and were jointly awarded the Davy Medal in 1903.  
 What's Radioactivity?
Radioactivity is the spontaneous disintegration of an unstable nucleus, by the emission of a small particle (i.e. an alpha-particle or a beta-particle) or by the change of the energy level of the nucleus by the emission of a gamma-ray.

In other words, elements may change into another element naturally due to unstable nucleus.

"Radioactivity is an atomic property of matter and can provide a means of seeking new elements. -Mme. Curie, Nobel Lecture, December 11,1911

Notes:

Question: What did Marie Curie discover?

Answer: Marie Curie studied the radiation of all compounds containing the known radioactive elements, including uranium and thorium, which she later discovered was also radioactive. She also found out that:
- you can exactly measure the strength of the radiation from uranium;
- the intensity of the radiation is proportional to the amount of uranium or thorium in the compound - no matter what compound it is;
- the ability to emit radiation does not depend on the arrangement of the atoms in a molecule; it must be linked to the interior of the atom itself.

When she realized that some uranium and/or thorium compounds had stronger radiation than uranium, she made the following hypothesis: there must be an unknown element in the compound which had a stronger radiation than uranium or thorium. Her work aroused the interest of her husband, Pierre Curie, who stopped his own research on crystals and joined the "detective work" with his wife. And Marie was proven right: in 1898 the Curies discovered two new radioactive elements: radium (named after the Latin word for ray) and polonium (named after Marie's home country, Poland).

-------------
The Curies (1898), France - discovered radium and polonium when they started to investigate radioactive substance

--------------
Marie Curie was interested in the recent discoveries of radiation.(She was finding a topic for her Doctorate Thesis) Wilhelm Conrad Roentgen had discovered X rays in 1895, and in 1896 Antoine Henri Becquerel had discovered that the element uranium gives off similar invisible radiations. Curie thus began studying uranium radiations, and, using piezoelectric techniques devised by her husband, carefully measured the radiations in pitchblende, an ore containing uranium.
---------------------

Advancements to the Atomic Theory
 Atomic Structure:

Alpha Radiation (+)

-2Protons and 2Neutrons(He) may be thrown out of a nucleus, thus making a new element different form the parent element. Atomic structure may not be the same.

Beta Radiation(-)

-Electron is thrown out of the nucleus.

Gamma Radiation
-electro magnetic wave with very high energy. 
-nucleus struggles to make itself stable
-------------------

Radioactive Decay (Alpha)

U²³⁸_{92  ---->He⁴2 + Th²³⁴90
Uranium will eventually become Thorium in time if it loses 2 protons.
---------------------}

Atomic Theory of Matter_:

_{(Dalton's Postulates)} 

(a)  All matter is composed of small, indivisible particles called atoms.

(b)  All atoms of a given element are identical in mass and properties.

(c)  Compounds are formed by a combination of two or more atoms in definite arrangements in the ratio of small whole numbers. 

(d)  Atoms are not created, destroyed or converted into other kinds of atoms during chemical reactions.  They are simply rearranged into new compounds.
_{-Mme Curie's work proved that the atoms of one element at least were not divisible. (A)}
-------------------------

Uses of Radioactivity

THE EARLY WORK OF MARIE AND PIERRE CURIE led almost immediately to the use of radioactive materials in medicine. In many circumstances isotopes are more effective and safer than surgery or chemicals for attacking cancers and certain other diseases. Over the years, many other uses have been found for radioactivity. Until electrical particle accelerators were invented in the 1930s, scientists used radiation from isotopes to bombard atoms, uncovering many of the secrets of atomic structure. To this day radioactive isotopes, used as "tracers" to track chemical changes and the processes of life, are an almost indispensable tool for biologists and physiologists. Isotopes are crucial even for geology and archeology. As soon as he understood radioactive decay, Pierre Curie realized that it could be used to date materials. Soon the age of the earth was established by uranium decay at several billion years, far more than scientists had supposed. Since the 1950s radioactive carbon has been used to pin down the age of plant and animal remains, for example in ancient burials back to 50,000 years ago. 
------------------

Without Marie Curie's discovery, the world would not be able to know the elements Radium and Polonium. Ernest Rutherford will not study about the radiation emitted by Thorium and Uranium, much less discover about the alpha and beta rays and natural transmutation on elements and perform his famous gold-foil experiment. Chemo Therapy would not be possible and Carbon dating would not be used.

Her achievements include a theory of radioactivity (a term that she coined), techniques for isolating radioactive isotopes, and the discovery of two elements, polonium and radium. Under her direction, the world's first studies were conducted into the treatment of neoplasms, using radioactive isotopes. She founded the Curie Institutes: the Curie Institute (Paris) and the Curie Institute (Warsaw).

Her husband and his brother had invented the electrometer, a sensitive device for measuring electrical charge. Using the Curie electrometer, she discovered that uranium rays caused the air around a sample to conduct electricity. Using this technique, her first result was the finding that the activity of the uranium compounds depended only on the quantity of uranium present. She had shown that the radiation was not the outcome of some interaction of molecules, but must come from the atom itself. In scientific terms, this was the most important single piece of work that she conducted.