This law was proposed by Henry Moseley in 1913, who discovered that the properties of the elements are more closely related to their atomic number (number of protons in the nucleus) than to their atomic mass.
The properties of the element are the periodic function of their atomic number.
The modern periodic table arranges the elements in order of increasing atomic number and groups them according to their chemical and physical properties. Elements in the same group have similar chemical and physical properties because they have the same number of valence electrons, which determine the element’s chemical behaviour.
