Thus by 1803 there were two known rare earth elements, yttrium and cerium, although it took another 30 years for researchers to determine that other elements were contained in the two ores ceria and yttria (the similarity of the rare earth metals' chemical properties made their separation difficult).
For instance, students who pursue a Ph.D. in psychology usually take from five to seven years depending upon required coursework as well as internship and supervised residency requirements.
Hereâs a basic breakdown of how long it might take to become a psychologist: Earn Your Bachelorâs Degree (Timeline: 4 to 5 Years) As noted earlier, you might want to begin by earning your undergraduate degree in psychology, but some people choose to pursue a degree in a related social science field.