ru·​bid·​i·​um | \ rü-ˈbi-dē-əm How to pronounce rubidium (audio) \

Definition of rubidium

: a soft silvery metallic element of the alkali metal group that reacts violently with water and bursts into flame spontaneously in air — see Chemical Elements Table

Examples of rubidium in a Sentence

Recent Examples on the Web The physicists used rubidium atoms that had been cooled to temperatures about a millionth of a degree Kelvin above absolute zero as a starting point for their plasma—an extremely cold temperature instead of the extremely hot one inside the sun. Karmela Padavic-callaghan, Wired, "An Ultracold Plasma Models the Universe’s Most Extreme Places," 17 Mar. 2021 The researchers reported that the rubidium atoms spent, on average, 0.61 milliseconds inside the barrier, in line with Larmor clock times theoretically predicted in the 1980s. Quanta Magazine, "Quantum Tunnels Show How Particles Can Break the Speed of Light," 20 Oct. 2020 Earth’s crust is abundant with a slightly radioactive isotope of rubidium that, over time, decays into strontium. Megan Gannon, Smithsonian Magazine, "Humans Have Been Taking Out Insurance Policies for at Least 30,000 Years," 9 Mar. 2020 The condensate is a cloud of rubidium atoms that has been cooled to nanokelvin temperatures. Dieynaba Young, Smithsonian Magazine, "Five Scientific Achievements That Happened During Coronavirus Lockdown," 15 July 2020 In this case, researchers are using laboratory-favorite rubidium, one of just a handful of elements known to form BECs. Caroline Delbert, Popular Mechanics, "Scientists Made the Fifth State of Matter ... in Space," 16 June 2020 Right now the setup uses rubidium atoms to make the BECs, but there are plans to incorporate potassium atoms into the mix to explore the physics of mixed BECs. Jennifer Ouellette, Ars Technica, "Chilling out: Physicists create exotic “fifth form of matter” on board the ISS," 15 June 2020 Researchers start with two identical stations in a single lab, each containing a cloud of rubidium atoms. Adrian Cho, Science | AAAS, "Quantum internet closer as physicists stretch spooky link between atoms," 13 Feb. 2020 The question is how to interpret the bizarre analogy between a fluid of rubidium atoms in a lab in Israel and the mysterious astrophysical abysses most often created when huge stars exhaust their fuel and collapse inward. Quanta Magazine, "Philosophers Debate New ‘Sonic Black Hole’ Discovery," 27 Aug. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rubidium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of rubidium

1861, in the meaning defined above

History and Etymology for rubidium

New Latin, from Latin rubidus red, from rubēre

Keep scrolling for more

Learn More about rubidium

Time Traveler for rubidium

Time Traveler

The first known use of rubidium was in 1861

See more words from the same year

Statistics for rubidium

Last Updated

19 Mar 2021

Cite this Entry

“Rubidium.” Dictionary, Merriam-Webster, Accessed 10 May. 2021.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

Keep scrolling for more

More Definitions for rubidium


ru·​bid·​i·​um | \ rü-ˈbid-ē-əm How to pronounce rubidium (audio) \

Medical Definition of rubidium

: a soft silvery metallic element that decomposes water with violence and bursts into flame spontaneously in air symbol Rb — see Chemical Elements Table

More from Merriam-Webster on rubidium Encyclopedia article about rubidium

Comments on rubidium

What made you want to look up rubidium? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

Star Wars Words Quiz

  • cu jedi training
  • The bounty portion of bounty hunters (such as Boba Fett) comes from a Latin word meaning
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Universal Daily Crossword

A daily challenge for crossword fanatics.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!