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.
One Year Master's Degree Programs. Some schools offer psychology master's degree programs that can be completed in approximately one year. Because all coursework must be completed within the one-year time frame, students are expected to enroll on a full-time basis.