Periodicity is the quality of occurring at regular intervals or periods (in time or space) and can occur in different contexts:* A clock marks time at periodic intervals. A metronome ticks at periodic intervals of time. A publication published at periodic intervals can be called a "periodical", for example a magazine. In mathematics, a function whose output contains values that repeat periodically is called a periodic function. In chemistry, the periodic table is a table which classifies the… (More on Periodicity)