Rhodium is element number 45, a metal with the symbol Rh. Its name comes from the Greek word for “rose.”
Atomic number 45102.9
RhRhodiumロジウム (rojiumu)
Symbol
Rh
Atomic weight
102.9
Place in the table
Period 5 · Group 9
Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.
Rose-colored water
When rhodium compounds are dissolved in water, the solution is rose-colored, which gave it its name. It was discovered in 1803.
Palladium, osmium and iridium were also discovered in 1803.
Where it sits on the table
Rhodium is in the fifth row of Group 9, with cobalt above and iridium below. Iridium’s name means “rainbow,” so the rose and the rainbow line up in one column.
Think about it
Q1Isn’t it surprising that a metal makes a rose-colored solution?
Q2Are there other elements named after flowers?
Q3Why do you think similar elements were found together in 1803?
There is no single right answer. Talking it over with someone at home is a good way to learn.
Did you know? — Elements named for colors include rhodium (rose), iridium (rainbow), chromium (color), chlorine (yellow-green) and iodine (violet).