Answer:
Elements in the same period have the same number of electron shells; moving across a period (so progressing from group to group), elements gain electrons and protons and become less metallic. This arrangement reflects the periodic recurrence of similar properties as the atomic number increases.
Step-by-step explanation:
The Periodic Table can predict the properties of new elements, because it organizes the elements according to their atomic numbers. ... They hope that the two nuclei at the centre of these atoms will fuse and form a heavier nucleus. When these heavy elements form, they are usually highly unstable.