General Information (Q-R)

Radiation - Radiation is the emission of energy rays from an object. In particular the term is applied to the emission of X-rays.

Radioactive - Radioactive elements are those of high atomic weight (radium, thorium, uranium etc.) which spontaneously emit alpha, beta or gamma rays.

Radioactivity - Radioactivity is the spontaneous disintegration of an atomic nucleus to produce more stable nucleus and accompanied by the emission of charged particles and possibly also gamma rays.

Radium - Radium is a radioactive gaseous element with the symbol Ra.

Rain - Rain is condensed moisture from the atmosphere which falls to the ground in visible separate drops.

Red-lead - Red-lead is an oxide of lead used as a red pigment.

Rhenium - Rhenium is a metal element with the symbol Re.

Rhodium - Rhodium is a metal element with the symbol Rh.

Rose's Metal - Rose's metal is a fusible alloy consisting of 50 per cent bismuth, 25 percent lead and 25 per cent tin.

Rust - Rust is an iron oxide.

Ruthenium - Ruthenium is a metal element with the symbol Ru.

Rutherfordium - Rutherfordium is an artificial radioactive element with the symbol Rf and with a very short lifespan.