[neilep (OP)]

Hullo, I'm Sheepy,


Metal !...metal is just great...it's shiny, can be heavy...magnetic...can be used to make stuff. and is featured as an ingredient in one of my friends hips !...which is nice.


Look here's a fine selection :



A Fine Selection Of Metals Just Seconds Ago !


...


Apparently defining ' metal' is a little ambiguous.... so.. which metal has the most ' metallic' properties and which metal has the least ?...is there a borderline metal/non metal ?




whajafink ?




Sheepy
xxxx

[paul cotter]

Indeed there are. Several elements have both metallic and non metallic allotropes, such as arsenic, antimony and selenium. Tin is normally considered a metal but it can also exist as a non metal. Hydrogen under enormous pressure has a metallic allotrope and I think phosphorus, a non metal can exhibit a metallic form but I am far from certain on that score.  PS: I just looked at the periodic table and it did not include selenium as a metalloid and instead listed tellurium. One I missed was silicon but also included is germanium which I would have thought to be a metal.

[Halc]

Linguistically, nothing says metal better than 'Iron'.  The called the first warship of the USA 'Old Ironsides' because the cannon balls just bounced off it, even though it was due to about 2/3 meter of oak and not iron at all.  'Steel' also has similar connotations.

As for elements with some of the strongest 'most metallic' properties, you want to go as far left in the periodic table as possible.  There is the naturally occurring Cesium, bested only by not-naturally occurring francium (ever heard of that?).  Not sure what those metallic properties are. Sure, alkaline (highly reactive), but there's other nice properties like strength (alloys are best), electrical conduction (gold, copper, soft stuff all).  Hard to pick one.

[evan_au]

is there a borderline metal/non metal ?

In the periodic table shown here ( https://en.wikipedia.org/wiki/Periodic_table ), there is a dotted line showing the approximate border between metal and non-metal.

One of the characteristics of a metal is that it tends to give up an electron in a chemical reaction.
- In the elements down the bottom rows of the periodic table, the outer electrons are shielded by many shells of inner electrons, so they are more "willing" to give up an outer electron
- This is why the fuzzy borderline extends farther to the right in the lower rows of the periodic table.
- Conversely, in the top row/upper left, Hydrogen is close to the border. It is able to give up its sole electron in an acidic water solution. Under immense pressure (eg deep inside Jupiter), it is able to conduct electricity.

[Bored chemist]

Metals are characterised by delocalised electrons. This often makes them strong, but there are plenty of exceptions. It also makes them, "shiny"
From the point of view of chemistry, the characteristic property of metals is their ability to give up some of those electrons to form ions.

On that basis, the most metallic elements are things like the heavy alkali and alkaline earth metals; caesium, barium  and francium.

On the other hand those metals are some of the softest.

So, the most metallic elements are also among the least metallic.

For extra giggles, ask an astronomer/ astrophysicist.
They consider everything except hydrogen and helium to be metals.
That's particularly ironic given that hydrogen apparently can act as a "proper" metal- i.e. it can have delocalised electrons.

[vhfpmr]

not-naturally occurring francium (ever heard of that?)

Lithium, Sodium, Potassium, Rubidium, Caesium, Francium, one of the few things I remember from school chemistry lessons, mainly because they put on a good show when you drop them in water.

[Bored chemist]

I rather doubt you saw anyone drop francium into water.

[evan_au]

This is what 1 gram of cesium looks like in water, from the Periodic Table of Elements series of videos:

The action starts at 3:45 (the rest is chemistry and engineering)

Potassium is more spectacular:

The action starts at 0:45

There is a video about Francium

They showed some pictures that purported to be Francium in water, but I suspect were relabeled atomic bomb tests.
The longest-lived isotope of Francium has a half-life of 20 minutes, which prevents accumulating any significant amount of Francium to drop it in water.
However, measurements show that Francium is slightly less reactive than Cesium, due to relativistic effects (mentioned around timestamp 12:30)
https://en.wikipedia.org/wiki/Isotopes_of_francium

[vhfpmr]

I rather doubt you saw anyone drop francium into water.

Where did I say I saw someone drop francium in water?

[Bored chemist]

Where did I say I saw someone drop francium in water?

Here.

Lithium, Sodium, Potassium, Rubidium, Caesium, Francium, one of the few things I remember from school chemistry lessons, mainly because they put on a good show when you drop them in water.

Unless the chemistry lesson was memorable because of a show you didn't see.

[chiralSPO]

I believe silver is the most conductive of the metals (under standard conditions).

Linguistically, gold might be considered the fundamental metal, at least in written Chinese (traditional), where the symbols of all the metals include the symbol for gold (on the left):

Gold: 金
Silver: 銀
Iron: 鐵
Rhenium: 錼
Sodium: 鈉
Brass: 黃銅
etc. etc.

Others have already mentioned metalloids, or semi-metals, like silicon, germanium, arsenic etc., which are elements that have some metallic characteristics, but are not actually metallic. Which would be a reasonable case for "least metallic metals." It is also important to point out (as Bored Chemist did) that elements (and compounds) can be metallic under some temperatures and pressures, and non-metallic at others.


What I will add to the discussion of "least metallic metals" is that there are some materials that have a metallic electronic structure in some directions/dimensions, but not others. A good example of this is graphite--within each graphene plane, electrons are fully delocalized in an extended pi system, but there is limited electronic interactions between the layers (so we can say graphite is a 2D metal). There are also 1D metals, like extended cumulenes/polyalkyenes or polythiazyl (-S-N-S-N-S-N-S-N-). Perhaps a 1D metal is a good candidate for "least metallic"

[paul cotter]

Polythiazyl rings a bell. Made from tetrasulphur tetranitride, if you don't blow yourself up in the process!

[evan_au]

Perhaps a 1D metal is a good candidate for "least metallic"

In a discussion on superconductors, the speaker pointed out that 2D superconductors operate at higher temperatures than 3D superconductors. He speculated that maybe room-temperature superconductors exist, but they may be 0D superconductors?

Are there materials/compounds which acts as 0D metals?
- What about benzene rings?

[paul cotter]

0D? That sounds to me like extrapolation ad absurdum.

[Bored chemist]

Linguistically, gold might be considered the fundamental metal,

And yet, here it is, behaving as a non-metal and forming a negative ion.
https://en.wikipedia.org/wiki/Caesium_auride

And here it is pretending to be the non metal, in a salt where an organic ion is taking the place of the metal.
https://en.wikipedia.org/wiki/Tetramethylammonium_auride

[Bored chemist]

Are there materials/compounds which acts as 0D metals?

The thing that usually defines metals is a delocalised electron.
Can you delocalise something in zero dimensions?
I don't think so.

[alancalverd]

If the delocalised electron defies a metal, then an electron in a π-bond or similar might be considered a 0D metal, however pointless that exercise might be. The bond is spatially localised but there is no way of knowing where the charge resides at any time.

[Bored chemist]

The smallest aromatic that I can think of is small, but certainly not zero dimensional.
https://en.wikipedia.org/wiki/Cyclopropenium_ion

[alancalverd]

So the electron itself can't be considered a metal? 

[Bored chemist]

Would a stationary electron in a vacuum be shiny?
I think it might be at sufficiently low photon energies.

For shorter wavelengths the momentum transfer to the very lightweight electron would mess things up.

But... that's physics not chemistry and I don't think physicists know the difference between metals and non metals.