caesium
Soft metallic element
Caesium is the British spelling of cesium, a soft, silvery-gold metallic element.
It is highly reactive—igniting spontaneously in air and exploding on contact with water.
Caesium is used in atomic clocks, which define the modern second.
The caesium fountain clock is accurate to one second in 300 million years.
Accuracy of measurement
- synchronizationAligning timing across systems
- UTCUniversal time standard
- oscillatorCyclic signal generator
- metrologyScience of precise quantification
GPS · microwave · navigation · calibration · horology · chronometry
Rarest occurring natural element
- rubidiumAlkali metal, atomic thirty-seven
- potassiumNineteenth element, symbol K
- sodiumEleventh element, highly reactive
- lithiumLightest solid element
isotope · ductile · malleable · silvery · electropositive · ion · cation · spectroscopy
Bright yellow, or precious
- yellowHue between green and orange
- emissionDischarged substance or act
- luminousEmitting or reflecting light
- incandescentGlowing from heat
Prone to sudden detonation
- hydrogenSimplest atomic element
- ignitionStarting combustion process
- vigorousHaving great physical energy
- flammableProne to ignition
corrosive · oxidation · hydroxide · chloride · compound · alkaline · exothermic · glovebox
Ant acid derivative
- magnetometerInstrument measuring field strength
- spacecraftVehicle for outer space
- radiotherapyMedical radiation for cancer
- photocellLight-sensitive electronic component
precision
Accuracy of measurement
- synchronizationAligning timing across systems
- UTCUniversal time standard
- oscillatorCyclic signal generator
metrology · GPS · microwave · navigation · calibration · horology · chronometry
francium
Rarest occurring natural element
- rubidiumAlkali metal, atomic thirty-seven
- potassiumNineteenth element, symbol K
- sodiumEleventh element, highly reactive
lithium · isotope · ductile · malleable · silvery · electropositive · ion · cation · spectroscopy · Bunsen
golden
Bright yellow, or precious
- yellowHue between green and orange
- emissionDischarged substance or act
- luminousEmitting or reflecting light
incandescent · photoelectric · scintillation · fluorescent · infrared
explosive
Prone to sudden detonation
- hydrogenSimplest atomic element
- ignitionStarting combustion process
- vigorousHaving great physical energy
flammable · corrosive · oxidation · hydroxide · chloride · compound · alkaline · exothermic · glovebox · ampoule
formate
Ant acid derivative
- magnetometerInstrument measuring field strength
- spacecraftVehicle for outer space
- radiotherapyMedical radiation for cancer