The modern periodic table of elements is comprised of (1) ____________ known elements and accepted by the International Union of Pure and Applied Chemistry. In this periodic table of elements, 25 belongs to the (2) ____________, that are known to have an atomic number greater than 92. Among these 25 elements, (3) ____________ is the only element in the group that is considered the heaviest naturally occurring radioactive element on earth. In the past, (4) ____________ is first chemist who proposed the idea of arranging the element in a tabular form. In his work, he found some irregularities in terms of chemical properties of elements. This caused him to make blank spaces in his periodic table for he assumed that there are elements that are yet to be discovered. With this, he is considered the (5) ____________ On the other hand, (6) ___________, a British physicist, discovered the correlation between the number of proton and the x-ray frequencies emitted by an element. His discovery led to a much better arrangement of elements in the periodic table. His work modified the (7) ____________ which now states that the properties of the elements are a periodic function of their atomic numbers. (8) ____________ allows the conversion of one element to another, artificially. The invention of the (9) ____________ aids the transmutation of heavier elements. In the process of converting one element to another, there are different types of particle in the nuclear reaction are involved. These are proton, neutron, (10) ____________, beta particles, and gamma particles.​