Video Transcript
What is the element classification
of the modern periodic table based on?
To understand how the elements of
the modern periodic table are arranged and classified, we need to consider the work
of three scientists. In 1913, a British scientist by the
name of Henry Moseley was studying the pattern of lines produced on a photographic
plate when an element emitted X-rays. Through some calculations, Moseley
was able to directly relate the pattern of lines produced to an element’s atomic
number. Based on his work, he suggested
that elements should be organized by increasing atomic number.
In the same year, Niels Bohr
proposed a new model of the atom. Bohr suggested that electrons in
the atom orbited the nucleus in discrete regions called energy levels. Bohr’s model would be expanded upon
over the years to include energy sublevels and orbitals.
In 1920, Ernest Rutherford
discovered a new subatomic particle, the proton. The number of protons in an atom of
an element was found to be equal to the element’s atomic number. The elements in the modern periodic
table are arranged based on all of these discoveries. The elements in the modern periodic
table are organized in order of increasing atomic number or increasing number of
protons. The elements are also organized
according to how the electrons fill various energy levels and sublevels. Elements found in the same column
or group have similar properties because the electrons in atoms of these elements
have a similar electron arrangement.
In addition, atoms of elements
found in the same row or period have the same number of electron shells or energy
levels. So, the elements of the modern
periodic table are classified or arranged based on the atomic number and the way of
filling energy sublevels with electrons.
