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.
1 Clinical Psychologist: Doctorate Degree in Psychology (4 to 7 years of graduate school). 2  Industrial-Organizational Psychologist: Masterâs Degree (2 to 3 years of graduate school). 3  Forensic Psychologist: Masterâs Degree (2 to 3 years of graduate school); a doctoral degree is recommended.o determine how long it will take you to become a psychologist, look into the specifics of the career you are interested in. As requirements vary by state, youâll want to research your stateâs licensing requirements before applying to any graduate program.