Question Video: Recalling How the Elements Are Arranged in the Modern Periodic Table | Nagwa Question Video: Recalling How the Elements Are Arranged in the Modern Periodic Table | Nagwa

# Question Video: Recalling How the Elements Are Arranged in the Modern Periodic Table Science • Second Year of Preparatory School

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What is the element classification of the modern periodic table based on?

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### 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.

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