[DOC] [TLE] Timeline of chemical element discoveries - Wikipedia [PAR] The discovery of the 118 chemical elements known to exist today is presented 
here in chronological order. The elements are listed generally in the order in 
which each was first defined as the pure element, as the exact date of discovery 
of most elements ... Given is each element's name, atomic number, year of first 
report, name of... [DOC] [TLE] Synthetic element - Wikipedia [PAR] In chemistry, a synthetic element is a chemical element that does not occur 
naturally on Earth, and can only be created artificially. So far, 24 synthetic 
elements have been created (those with atomic numbers ... on Earth. All are 
transuranium elements and have atomic numbers of 95 and higher. ... Plutonium, 
Pu, 94, 1940... [DOC] [TLE] transuranium element | chemical element | Britannica.com [PAR] The others, which have atomic numbers higher than 103, are referred to as the ... 
Fermi found were lighter, known elements formed by the splitting, or fission, of 
uranium.) Not until 1940 was a transuranium element first positively produced 
and... [DOC] [TLE] Check and uncheck as needed to select sections to print. Then ... [PAR] All the atoms of a particular element have the same atomic number, but they are 
.... Until 1940 the element with the highest known atomic number was uranium... [DOC] [TLE] The Periodic Table - Infoplease [PAR] Although some elements, such as gold and iron, have been known to humans ... 
it wasn't until the 17th century that the first scientific discovery of an element ... by 
order of increasing atomic number, which equals the number of protons in the ... 
Most of these changes were the work of American chemist Glenn Seaborg, who... [DOC] [TLE] Atomic Structure Timeline [PAR] He discovered that the properties of elements "were periodic functions of the their 
atomic weights". This became known as the Periodic Law. ... charge; cause 
pinwheels in their path to spin indicating they have mass. ... 1900, Max Planck, 
used the idea of quanta (discrete units of energy) to explain hot glowing matter. [DOC] [TLE] The Periodic Table - Western Oregon University [PAR] As the number of known elements grew, scientists began to recognize patterns ... 
In 1817 Johann Dobereiner noticed that the atomic weight of strontium fell ... 
triads of elements the middle element had properties that were an average of the 
... the scientific community via publication (1869) before Meyer's appeared (1870)
. [DOC] [TLE] Element, chemical - Science in Context - Gale [PAR] Most of these synthetic elements have atomic numbers higher than 92 (i.e., more 
... been known for thousands of years and that already had Latin names before ... 
There it stayed until 1940, when synthesis of the transuranium elements began. [DOC] [TLE] Atoms facts, information, pictures | Encyclopedia.com articles about ... [PAR] This was before the discovery of the nucleus, where the protons and neutrons 
reside at the heart of the atom. ... Atoms of the same element always have the 
same number of protons, and ... Electrons are perhaps the most intriguing parts of 
an atom. ... Democritus, who actually articulated these ideas (far less is known 
about... [DOC] [TLE] Elusive Element 113 Finally Created, Researchers Say - Live Science [PAR] Sep 26, 2012 ... Heavier and heavier synthetic elements have been created over the years, with 
the most massive one being element 118, temporarily named ununoctium. ... 
Until now, only scientists in the United States, Russia and Germany have had ... 
For each proton, atoms generally have roughly the same number of... [DOC] [TLE] Plutonium - Periodic Table of Elements: Los Alamos National ... [PAR] Atomic Number: 94, Atomic Radius: 243 pm (Van der Waals) ... Element 93 was 
discovered in 1940/41 by Glenn T. Seaborg, Edwin M. McMillan, J. W. ... 50% 
greater than that of 235U, the best fissioning element known at that time. ... The 
second atomic bomb used had a plutonium core and was nicknamed "Fat Man"... [DOC] [TLE] C&EN: IT'S ELEMENTAL: THE PERIODIC TABLE ... [PAR] ... (

Question: Until 1940 this element had the highest known atomic number
Answer: Uranium