Row 6: caesium to radon
Row 6: caesium to radon: a chapter of The Periodic Table Book, with each element's symbol, number and story.
17 cards · Science
Each Zap teaches up to 5 new cards, so you learn the chapter a few at a time.
Checked by the Brain Zap team · reviewed 27 Oct 2026
Sources: Periodic Table of Elements (IUPAC), Periodic Table (Royal Society of Chemistry)
Preview
Symbol: Cs
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Caesium
Learn more: Atomic clocks count the vibrations of caesium atoms: 9,192,631,770 of them make one second.
Symbol: Ba
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Barium
Learn more: A barium drink shows up white on X-rays of the gut; it also turns fireworks green.
Symbol: Hf
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Hafnium
Learn more: Hafnia is Latin for Copenhagen, where it was found in 1923; it goes into nuclear reactor control rods.
Symbol: Ta
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Tantalum
Learn more: Named after Tantalus of Greek myth; it shrugs off acid and is used in phone capacitors.
Symbol: W
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Tungsten
Learn more: W is for wolfram. It has the highest melting point of any metal, about 3,422 °C.
About this topic
The sixth row is the longest of all. This chapter covers its two first elements and the row after the lanthanides, which have a chapter of their own. Here are the heavy metals of jewellery and industry: tungsten, platinum, gold, mercury and lead, many with symbols from their Latin names. The row ends with polonium, astatine and radon, three radioactive elements found by chemists in the late 1800s and 1900s.
This is a chapter of The Periodic Table Book. Each card shows a symbol or an atomic number and asks for the element's name, with a hint before you answer and a fact after.
All 17 cards
Symbol: Cs
Caesium
Learn more: Atomic clocks count the vibrations of caesium atoms: 9,192,631,770 of them make one second.
Symbol: Ba
Barium
Learn more: A barium drink shows up white on X-rays of the gut; it also turns fireworks green.
Symbol: Hf
Hafnium
Learn more: Hafnia is Latin for Copenhagen, where it was found in 1923; it goes into nuclear reactor control rods.
Symbol: Ta
Tantalum
Learn more: Named after Tantalus of Greek myth; it shrugs off acid and is used in phone capacitors.
Symbol: W
Tungsten
Learn more: W is for wolfram. It has the highest melting point of any metal, about 3,422 °C.
Symbol: Re
Rhenium
Learn more: One of the last stable elements to be found, in 1925; it goes into jet engine blades.
Symbol: Os
Osmium
Learn more: Its name means smell, for the sharp odour of its oxide; it is the densest natural element.
Symbol: Ir
Iridium
Learn more: A thin iridium-rich layer of rock worldwide points to the asteroid that ended the age of the dinosaurs.
Symbol: Pt
Platinum
Learn more: Its name means little silver; it is used in jewellery and in catalytic converters.
Element 79
Gold
Learn more: Au comes from aurum. It is so soft that one gram can be beaten into a sheet about a metre across.
Symbol: Hg
Mercury
Learn more: Hg is from hydrargyrum, liquid silver; it filled thermometers until people learned how toxic it is.
Symbol: Tl
Thallium
Learn more: Named for the bright green line in its light; it was once used as a rat poison.
Symbol: Pb
Lead
Learn more: Plumbers are named after it: Roman water pipes were made of lead.
Symbol: Bi
Bismuth
Learn more: Its crystals grow in colourful stepped shapes, and it is in some stomach medicines.
Symbol: Po
Polonium
Learn more: Marie and Pierre Curie found it in 1898 and named it after Poland.
Symbol: At
Astatine
Learn more: Under a gram of it is thought to exist in Earth's crust at any moment; its name means unstable.
Element 86
Radon
Learn more: It seeps from rocks into houses and is a leading cause of lung cancer after smoking.
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