Prescription painkillers, also known as opioid pain relievers, include oxycodone, hydrocodone, hydromorphone, and others. Many people who abuse these painkillers become dependent. Some even move on to abusing illegal narcotics, such as heroin.
The first 92 (through uranium) occur naturally. The others are transuranics.. As of 2009, there are 118 ending with ununoctium. All together there are 117 elements on the periodic table, 94 of which occur naturally on earth. According to Wikipedia, there are 117 elements that have been isolated or synthesized, with a gap between element 116 and element 118.
Periods (rows) are the horizontal arrangements of the elements. . Elements in the same Period have the same number of occupied electron shells (energy levels) . There are seven (7) periods on the Periodic Table of the Elements. Periodic Law: The properties of the elements are periodic function of their atomic numbers. In other words, by arranging the elements in the order of increasing atomic numbers, elements with similar. properties end up in the same group.