periodic table
When ordered by atomic number, the discrepancies within Mendeleevs table disappeared. Tellurium has an atomic number of 52, while iodine has an atomic number of 53. Even though tellurium does indeed have a greater average atomic mass than iodine, it is properly placed before iodine in the periodic table. Mendeleev and Moseley are credited with formulating the modern periodic law , which states that when elements are arranged in order of increasing atomic number, there is a periodic repetition of their chemical and physical properties. We will discuss some of these chemical and physical properties later on in this chapter. The result is the periodic table as we know it today.