Henry Moseley is credited with one
of the most important discoveries in the field of chemistry. At a very
young age of 26, Moseley showed how each element's atomic number was
greater by one unit in the periodic table. Using the skills
Moseley developed, he was able to confirm Mendeleev's periodic table
and other issues that continued to rise with the periodic table.
Moseley helped fill in the gaps that remained and also predicted there
were seven gaps that had been undiscovered. These gaps were atomic
numbers 43, 61, 72, 75, 86, 87, and 91. Moseley's method brought a new
light to the periodic table and helped answer a lot of issues that were
plageing scientist before him such as the location of tellurium and
iodine, and the location of cobolt and nickel. Moseley's life was cut
short when he died during World War I. Excluding a small group of
scientist, Moseley was not very well known in his field but his work
that he left behind made him a legend in the field of Physics forever.
Moseley started his career off working under Ernest Rutherford.
Rutherford could tell early on that Moseley had great potential in the
world of physics. After working with Rutherford, Moseley moved on to
try and test van den Broek's work containing the organization of
elements by their atomic number. Moseley had come into close contact
with a young Niels Bohr and was well aware of Bohr's work with atomic
spectra. Moseley developed an apparatus to test the K alpha X-rays
would be measured. When Moseley first started to test his experiment,
he used 14 different elements. Out of the fourteen elements he chose,
nine of the those elements were determined to have a contineous series
on the periodic table. Those nine elements are from titanium to zinc.
The diagram below was the chart Moseley created by plotting the
frequency of the lines from the K series of the spectral lines that
were produced by his experiment. He then determined from this plot that
the frequencies of lines from the K series of spectral lines was
directly proportional to the square of the integer. When this discovery
was made Moseley started to quickly realize his results were showing
how each element's K series of Spectra Lines was showing the position
of each element on the periodic table in increasing order of one unit.