Elemental

No one has ever seen astatine, which shares the distinction of being one of the rarest naturally-occurring elements on earth. Find out more with Allan Blackman from AUT in episode 8 of Elemental.

Astatine is an enigmatic chemical element whose name means unstable.

Along with francium, astatine has the distinction of being the rarest naturally-occurring element on earth. Ironically, element 85 was actually synthesised in the laboratory before it was finally found in nature.

Professor Allan Blackman from Auckland University of Technology tells us everything we know about astatine - which is not much.

The Elemental podcast is celebrating 150 years since the periodic table was first published by Russian chemist Dmitri Mendeleev.

We are exploring the periodic table alphabetically, and astatine is the last of the As. So far we have looked at actinium, aluminium, americium, antimony, argon and arsenic.

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Arsenic is a well-known killer that was once dubbed 'succession powder'. Join Allan Blackman from AUT in episode 7 of Elemental, a journey through the periodic table.

Arsenic is probably the most well-known poison, and it is associated with equally famous names, from Napoleon Bonaparte (did his arsenic green wallpaper really kill him?) to the famous race horse Phar Lap (was he deliberately poisoned).

Professor Allan Blackman from AUT explores arsenic, and finds out that for a few animals, at least, it may actually be a vital trace element.

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Argon is in every breath you take and its inertness is its best feature, as we discover with AUT chemistry professor Allan Blackman, in episode 5 of Elemental.

Argon is in every breath you take and its inertness is its best feature, says Elemental's in-house chemistry expert Professor Allan Blackman, from Auckland University of Technology.

Argon (symbol Ar and number 18) is a noble gas. Its inertness makes it useful in situations such as arc-welding and incandescent light bulbs, to prevent combustion.

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Antimony can be used to take lives - and to save lives. Check out episode 4 of Elemental with Professor Allan Blackman from AUT.

Antimony can be used to take lives - and to save lives. Check out episode 4 of Elemental with Professor Allan Blackman from AUT, as he shares the varied uses of antimony (chemical symbol Sb and element number 51).

Compounds of antimony have uses ranging from hardenng lead in printing presses to the black eyeliner beloved of early Egyptians.

Antimony might ring bells if you've listened to William Ray's Black Sheep podcast from RNZ - it features in the story Poisoner: the story of Thomas Hall. And if you haven't already listened, it comes highly recommended.

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Invented during war, radioactive americium has become a bit of a do-gooder that is in most homes. Find out more with AUT's Allan Blackman in episode 3 of Elemental.

Invented during war, radioactive americium has become a bit of a do-gooder that is - surprisingly - in most homes.

Professor Allan Blackman from AUT tells us how the heavy element 95 was discovered during the Manhattan Project and named geographically - after America - because it sits near the bottom of the periodic table below Europium, which is named after Europe.

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Aluminium is a light, well-known metal with lots of useful properties. Join AUT chemistry professor Allan Blackman for episode 2 of Elemental.

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The first alphabetical element in the periodic table is actinium. It is a heavy radioactive element, as we discover in episode 1 of Elemental, with Professor Allan Blackman from AUT.

CORRECTION:

In the audio we mistakenly said that Cherenkov radiation happens when particles travel faster than the speed of light. Listener Jennifer Narang wrote in with this helpful and correct explanation:

"Cherenkov radiation is not the result of a particle traveling faster than the speed of light (which is physically impossible). It's due to a particle traveling faster than the PHASE SPEED, which is a totally different animal.

Imagine I were singing scales, going up and down and up and down with my voice. How fast I ran through the notes and returned to my original note, that would be my phase speed. That's completely unrelated to how fast those sound waves - whatever their frequency - are traveling from my mouth to your ears.

Hope this explanation helps shed light on Cherenkov radiation!"

It certainly does help - many thanks.

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In the prequel to Elemental, AUT's Allan Blackman introduces us to Dmitri Mendeleev and chemistry's periodic table of elements.

Follow and listen to Elemental on Apple Podcasts, Spotify, YouTube or wherever you get your podcasts.

One hundred and fifty years ago the Russian chemist Dmitri Mendeleev published his version of the Periodic Table of the Elements.

To commemorate this, the United Nations has designated 2019 as the International Year of the Periodic Table.

Most of us haven't thought about the periodic table since high school, so why all the fuss?

Okay. Let's suppose you were going to build a Universe from scratch. How many fundamental building blocks would you use to create everything in your Universe? Millions, billions, surely?

No.

It transpires that our Universe consists of only 118 different fundamental building blocks. We call these atoms. And any collection of a single type of atom we call an element.

You will be familiar with some elements - hydrogen, carbon, aluminium and gold, for example. Others, such as promethium, technetium, erbium, and rhenium, for instance, will probably be a mystery.

Back in the 1800s, chemists wanted to find some order to these elements. However, not all of the elements we know today had been discovered. Only around 30 were known at the start of the 19th century and about 60 appeared on Mendeleev's Periodic table.

Despite the omissions, a number of chemists noticed that certain elements behaved chemically similarly; for example, the metals lithium, sodium and potassium were all known to react vigorously with water.

Mendeleev, and his contemporary Lothar Meyer, used these observations to independently order the known elements according to these similarities. However, Mendeleev gets the credit as he published first (there are no silver medals in science).

Mendeleev's stroke of genius was to leave gaps in his Periodic Table for unknown elements he was sure hadn't yet been discovered. He was spectacularly vindicated when the elements gallium and germanium were duly found a few years later.

Unbeknownst to Mendeleev, his Periodic Table (with a couple of small exceptions) ordered the elements according to their atomic number, which reflects the number of protons in the nucleus of the atom.

Given that the concepts of both protons and the atomic nucleus had to wait until New Zealand's own Ernest Rutherford in the early years of the 20th century, this further adds to the greatness of Mendeleev's discovery.

Both men are now immortalised on the Periodic Table: mendelevium is element 101 and rutherfordium is element 104)…

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