I would pronounce it "TEN-e-seen," like iodine and chlorine, but some people in America say "CHLOR-eyen" and "I-o-dyne."

But my feeling is that everybody will say "TEN-e-seen" because it sounds just like the state of Tennessee, whereas "TEN-e-syne" doesn't.

The reason why it was called tennessine is because Tennessee is the home of the Oak Ridge National Laboratory

where the berkelium that was used to make the element, to synthesise it,

the heavy target was made out of berkelium, and the berkelium sample was prepared in Oak Ridge.

Then, as before, we accelerate a light atom, calcium 48, a very expensive isotope of calcium, into the berkelium, and make Element 117, tennessine.

Now, I think that the interesting things about tennessine is to speculate about the chemistry.

The first thing is that you could wonder about its colour, if you could get a large lump of tennessine.

If you'll go down Group 17, fluorine is almost colourless, slightly green, and then as you go, to bromine is red, iodine is a dark purple colour.

Nobody knows what astatine looks like, and it's possible that tennessine might be a black gas, which would itself be really quite exciting.

Now, unfortunately the way these experiments are done is that, although you would expect tennessine being a halogen to exist as two atoms,

Tennessine 2 just like Cl2, you only make one atom at a time, so it's like some rare species of animal: there's just one in the zoo and you can't find a mate.

So we'll never know what Tennessine 2 looks like, because we can never get two atoms at the same time.

I would predict that Tennessine 2 would have a very weak bond, possibly the weakest bond between two atoms of the same type

that actually bond together, for example Helium doesn't bond to anything, but it would be a very, very weak bond.

The other thing which is interesting is to have a "flight of fancy."

Imagine what some of the compounds would be like.

And the one I would really like to see is "francium tennesside," a bit like sodium chloride, but with francium,

the element which loses an electron most easily from the alkaline metals, and tennessine.

And I would predict that francium tennesside would form crystals which are really quite flexible.

If you take caesium iodide, higher up the Periodic Table, you can bend crystals of caesium iodide without breaking them.

You could probably make springs out of francium tennesside,

but it's so radioactive that you would be got by the radioactivity long before you made the spring!

...and there we have... oh, nearly two inches maybe of liquid fluorine. You can go right up that's, there's no problem with that.

You want to just clear a bit of the condensation off there

Yeah, I'm really surprised; I thought it would be pale green and it's really quite dark yellow.

If I'd been shown it I would have said it was liquid chlorine, but I've never seen liquid chlorine either.

I'm quite pleased with that. Yes.

I have been, as foreign secretary, giving quite a few of my notes and things to Keith to put in the archive,

so there will be at least some trace of me, even if you can't read my emails.