Embed Size (px)
Citation preview
HISTORY OF THE PERIODIC TABLE
What is the periodic table? How is it arranged?
A brief history
It all started with the philosopher Aristotle in 330 BC Thought that all things
are made up of one of four things Fire Earth Water Air
A brief history
It took a long time until someone looked at what made up everything on earth
In 1789 Antoine Lavoisier Wrote the first extensive
list of elements 33 elements in four
categories Distinguished between
metals and non-metals, gasses, and acids producers
A brief history
In1828 Jons Jacob Berzelius developed a table for elements based on atomic weights. Introduced letters
to symbolize elements Example:
H, O, etc.
A brief history
In 1864 John Newlands discovered that all of the known elements (there were <60) were arranged in order of atomic weights and observed similarities every 8th element He proposed the 'Law
of Octaves'. This turned out to be
incorrect
A brief history
Mendeleev Considered the father of
the modern periodic table In 1869 he produced a
table based on atomic weights but arranged 'periodically' with elements with similar properties under each other.
Gaps were left for elements that were unknown at that time and their properties predicted.
A brief history
He was able to used his table to predict the physical properties of three elements that were unknown at that time.
He stated that if the atomic weight of an element caused it to be placed in the wrong group, then the weight must be wrong.
Problems arose when new elements were discovered and more accurate atomic weights determined
A brief history
In 1914 Henry Moseley was able to determine the atomic number of each of the known elements Worked with He rearranged
the elements in order of increasing atomic number.
X-Rays He modified the 'Periodic
Law’ Periodic Law: When
elements are arranged in order of increasing atomic number, there is a regular pattern in their chemical and physical properties
A brief history
His research was stopped by the British government when is was forced to serve as a foot soldier in WWI.
He was killed in the fighting in Gallipoli by a sniper, at the age of 28.
Because of this loss, the British government restricted its scientists to noncombatant duties during WWII.
A brief history
Glenn Seaborg in 1944 created transuranic elements There were 10 elements
which he co-discovered He moved 14 elements out
of the main body of the periodic table below the Lanthanide series. These became known
as the Actinide series. These are the elements that
are after uranium in the periodic table (atomic number >92)
A brief history
He is the only person to have an element named after him while still alive. Seaborgium (Sg)- with
atomic number 106 "This is the greatest
honor ever bestowed upon me - even better, I think, thanwinning the Nobel Prize."
He died in 1999
