Praseodymium is element number 59, with the symbol Pr. Its name comes from the Greek for “pale green” and “twin.”
Atomic number 59140.9
PrPraseodymiumプラセオジム (puraseojimu)
Symbol
Pr
Atomic weight
140.9
Place in the table
Period 6 · Lanthanoids
Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.
The “green twin”
Praseodymium was discovered in 1885. It was found together with neodymium, hence “twin,” and its salts are green, hence “pale green.”
Its neighbor neodymium’s name means “new twin.”
Where it sits on the table
The fifteen elements from lanthanum to lutetium are called the lanthanoids. On the Room of the Elements table they are in the upper of the two rows set apart at the bottom.
Think about it
Q1What do you think of calling two elements found together “twins”?
Q2Collect the elements named for colors in the Room of the Elements.
Q3If three had been found together, what would you name them?
There is no single right answer. Talking it over with someone at home is a good way to learn.
Did you know? — Praseodymium and neodymium both end in “twin,” and they are neighbors on the periodic table.