Element 109 (meitnerium) is named after Lise Meitner, the most significant woman scientist of the 20th century. During her lifetime, Meitner had close professional alliances with many famous scientists including Ludwig Boltzman, Niels Bohr, Max Born, Max Planck, Wolfgang Pauli, James Chadwick and Albert Einstein (Einstein called Meitner "The German Madame Curie").  Aside from her scientific achievements, Meitner is remembered for her struggle in the face of adverse social, cultural & historical conditions.
So who was Meitner and what did she do?
 
 
 

Born in Austria (1878), Meitner was the third of eight children of a Jewish family. After receiving a doctorate in physics (1906) under Ludwig Boltzman (Boltzman constant and contributions in thermodynamics), Meitner took a position at the University of Berlin and worked in the basement-- the laboratory supervisor (Emil Fisher, Nobel Prize 1902) did not allow women in the laboratory. Shortly after arriving at the university, Meitner and chemist Otto Hahn formed a partnership that lasted for 30 years. Moving to the newly formed Kaiser Wilhelm Institute in 1913, Hahn and Meitner studied radioactivity utilizing her knowledge of physics and his knowledge of chemistry. In 1918, they discovered the element protactinium. In 1923, she explained the Auger effect (outer-shell orbital electrons ejected from the atom when they absorbed the energy released by other electrons falling to lower energies). Meitner was also a pioneer of the use of the Geiger counter in nuclear research, using them to test the passage of gamma rays through matter.
 
 
 
 
 

After Enrico Fermi (1934) showed that a heavy element bombarded with neutrons forms a heavier isotope of that element, Meitner and Hahn repeated and expanded the original experiments of Fermi. Due to her Jewish heritage, Meitner was forced to leave Germany (1938) and she fled to Sweden. Meitner continued to correspond with Hahn and at her urging, Hahn bombarded uranium with neutrons and found radioactive barium to form. Totally baffled by this result, Hahn wrote to Meitner asking, "Perhaps you can suggest some fantastic explanation!"

Meitner did have an explanation: The uranium atom had split! Using Einstein's equation (E = mc²), she made calculations showing the formation of barium, krypton, additional neutrons, and energy. Bombarding ²³⁵U with a neutron results in the formation of ²³⁶U. Subsequently ²³⁶U splits into barium, krypton, 3 additional neutrons, and an enormous amount of energy. The 3 neutrons can strike three ²³⁵U nuclei and generate 9 neutrons, which can generate 27 neutrons, and so on (chain reaction). Meitner named the process "fission" after cell division in biology.
²³⁵U  +  ¹n ²³⁶U ¹⁴¹Ba  +   ⁹²Kr  +  3 ¹n  +  energy

Hahn received the Nobel prize in chemistry and Meitner continued to work first at the Swedish Royal Academy and then at the Swedish Atomic Energy Committee. In 1958, she moved to Cambridge, England, and fully retired in 1960. She passed away in 1968. Over her brilliant and prolific career, she published over 135 scientific papers, and was involved in the cutting edge of nuclear research for over 55 years.
 
 

Fission
To understand fission and the significance of Meitner's work, let's look at the atom. It consists of two regions: the nucleus (protons/neutrons) and outside the nucleus (electrons).  Nuclei with same number of protons but different number of neutrons are called isotopes; the sum of protons and neutrons known as mass number. Nuclei are held together by a strong binding energy, which counteracts the repulsive force of the positively charged protons. Some isotopes are very stable (iron) while other isotopes are unstable (uranium) and spontaneously disintegrate.

Einstein (1905) proposed that mass and energy were indeed equivalent and linked by E = mc² (E = energy, m = mass, c = speed of light). Therefore, even a small amount of mass is equivalent to a massive quantity of energy. The mass of the nucleus and the energy required to bind it are just different types of the same thing. As mass increases, binding energy decreases and the nucleus becomes less stable. There are two ways of splitting the atom: increase its energy or increase its mass. However, the energy needed to split an atom is enormous, and this is not a practical possibility. The other method (adding mass) is achieved by bombarding a suitable nucleus with neutrons. By adding an extra neutron to the nucleus, mass is increased, and binding energy is consequently reduced to conserve energy. When the binding energy is reduced, the electrostatic repulsion within the nucleus is greater than the binding energy, and the nucleus splits apart. When an nucleus splits, it is not simply a matter of that nucleus dividing in half to form two equal daughter nuclei. Instead, two (or more) daughter nuclei are formed with uneven masses, which do not add together to form the mass of the original nucleus.

The process of fission is not ordered or regular, and it is uncertain, just like any process. The two daughter nuclei are very rarely of even weight, and it is also rare that more than two are formed, although it is possible. The difference in mass of the two particles is proportional to the energy applied to the original nucleus during fission. Daughter nuclei are not the only products of fission; two or three neutrons are emitted for each split atom, and these can bombard more original nuclei, thus creating a chain reaction of constant fission until there are no original-type nuclei left. Einstein's mass-energy equivalence predicts that the missing mass is converted into a vast amount of energy (about 200 billion cal/g).
 
 

Element 109 is a synthetic element that is not found in nature. On August 29, 1982, it was made and identified by physicists of the Heavy Ion Research Laboratory, Darmstadt, West Germany, by bombing a target of Bi-209 with accelerated nuclei of Fe-58. If the combined energy of two nuclei is sufficiently high, the repulsive forces between the nuclei can be overcome.

²⁰⁹Bi  +  ⁵⁸Fe   ²⁶⁶Mt  +  ¹n

In this experiment it took a week of target bombardment to produce a single fused nucleus. The team confirmed the existence of Element 109 by four independent measurements. The newly formed atom recoiled from the target at predicted velocity and was separated from smaller, faster nuclei by a newly developed velocity filter. This experiment demonstrated the feasibility of using fusion techniques as a method of making new, heavy nuclei. The new element was named meitnerium to honor Lise Meitner (the name was recognized internationally in 1997). Only a few atoms of Mt have ever been made; it has a half-life of about 0.0038 seconds and no commercial applications.