The statement "The chemical and physical properties of elements are a periodic function of their atomic masses" refers to the concept known as the periodic law or periodicity in chemistry. It is one of the fundamental principles in the field of chemistry, first proposed by Dmitri Mendeleev in the late 19th century.
According to this law, when elements are arranged in order of increasing atomic mass, certain properties of the elements recur periodically. Mendeleev organized the elements into a tabular format, known as the periodic table, based on this principle.
The periodic table arranges elements in rows called periods and columns called groups or families. Elements within the same group exhibit similar chemical properties, while elements within the same period share certain physical properties. This periodic pattern arises due to the recurring pattern of valence electrons and electron configurations as atomic masses increase.
In summary, the statement means that the chemical and physical properties of elements exhibit a periodic pattern based on their atomic masses when arranged in the periodic table.