If an atom loses one of these, it becomes a cation, a positively charged ion
On Oct. 15, 2003 it became the third country to launch a man into space; the Shenzhou 5 spacecraft orbited the Earth 14 times
A 1 on the Mercalli scale or below a 3 on the Richter scale is only measurable by these devices
The tokamak, this type of nuclear reactor, uses plasma heated to 180 million degrees as fuel
(Cheryl of the Clue Crew at the Eli Whitney Museum in New Haven, Connecticut) In the 1940s, Dr. William Sewell created an artificial one of these, using parts from an erector set
In 1901 Eugene Demarcay discovered Eu, this rare-earth metal that's named for a continent
(Cheryl of the Clue Crew at the chalkboard) By adding two lines, I've turned a math symbol for division into a symbol for this
When William Ramsay told of the discovery of this gas on Earth in 1895, we wonder if he used a squeaky voice
Brighter in the night sky than any star is this planet that comes closest to the Earth
A hemoglobinometer measures the amount of hemoglobin in this