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.
The Periodic Table is an arrangement of the elements in order of atomic number. Columns in the table - groups. The elements in any one vertical column are said to be in the same group or family. Eight of the groups are numbered from left to right. Elements in the same group have similar chemical properties. The group number is the same as the number of electrons in the outer shell of all the elements in the group.