Atoms, Elements, Compounds
Completion requirements
Browse the glossary using this index
Special | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ALL
R
Radioactive isotope(radioisotope)— an isotope with an unstable nucleus that emits radiation. | |
Radiocarbon datinga method of estimating the age of ancient organic materials using carbon-14. | |
ReactantA starting substance in a chemical reaction. | |
Reaction arrow(→)– A symbol meaning "produces" or "forms" in a chemical equation. | |
Relative atomic massThe average mass of an atom of an element compared with one-twelfth of the mass of a carbon-12 atom. | |
ResidueThe solid remaining on the filter paper after filtration. | |
Retention factor(Rf)– The ratio of the distance travelled by a substance to the distance travelled by the solvent front. | |