[MarianaM (OP)]

Corey asks...

What is the most dangerous group of elements?

Can you help?

[evan_au]

As a group, the metals on the left-hand side of the periodic table are very reactive.

You can see demonstrations of their reactivity in the "Periodic Table of Elements" Youtube series; this one is Cesium:

As an individual element, Fluorine is particularly nasty - but by the time you get to other members of the same group, some people use iodine and bromine for medicinal purposes.

There are some other elements that are moderately safe in small quantities, but extremely dangerous by the time you get up to baseball size, like Plutonium.

[Hayseed]

A reactive metal or a reactive gas will invoke an immediate response......which might enable you to survive.  But you would not feel or sense a rich radioactive species, which would be killing you, without you knowing it, especially if you ingested or inhaled it.  Nothing in the environment would warn/alert you.

[chiralSPO]

I would say, as a group, the actinides are the "most dangerous"

[alancalverd]

All depends on the time of exposure (in utero, child, adult) duration of exposure, place of exposure (surface - fluorine, inhaled - polonium) latency period to clinical presentation, likely fatality once diagnosed.....

Corrosive chemical reagents like fluorine produce instant pain and can be remedied by amputation (it's usually fingers that get contaminated). Inhaled polonium produces complex symptoms which are usually fatal by the time they are diagnosed or even clinically significant. In utero exposure to plutonium and other alpha emitters tends to produce non-lifethreatening or at least treatable longterm disfigurement or cancer (particularly leukemia).

Pretty well any element with an atomic number greater than 8 (i.e. most of them) will kill you if swallowed or inhaled in elemental form ("noble gases" will suffocate you)  in sufficient quantity. And I wouldn't eat lithium beryllium or boron by choice.

[syhprum]

Not very reassuring as I am scheduled to be shot full of radio active Fluorine on Thursday !

[chiralSPO]

ALL substances are toxic at some dosage. They key is to determine which are toxic in small amounts.

[alancalverd]

Not very reassuring as I am scheduled to be shot full of radio active Fluorine on Thursday !

But it won't be in elemental form. It's usually attached to some glucose molecule or other. I wouldn't be too keen on raw sodium, but I always put its chloride on my chips, and my heart wouldn't function without some potassium ions from the chips themselves.

Interestingly, natural potassium is radioactive: I use a carton of "low salt" and a scintillation counter to demonstrate the dangers of following governmental dietary guidance.   

[syhprum]

I don't think the Sulphur hexa fluoride in the grid switchgear poses much danger these highly active chemicals are tamed when they are formed into suitable molecules.

[evan_au]

I would say, as a group, the actinides are the "most dangerous"

Isn't this group a period?

[Hayseed]

I have had eight radioactive scans since I have been disabled.  Other than losing a little weight, and not needing a night lite, I haven't noticed any effects.

[chiralSPO]

I would say, as a group, the actinides are the "most dangerous"

Isn't this group a period?

I suppose, technically (almost, they are part of a period)...
But actinides are more related to each other chemically than they are to, for instance, the lanthanides.

[Bored chemist]

I would say, as a group, the actinides are the "most dangerous"

Isn't this group a period?

Matter of definition.
"Elements that begin with the letter b" is a group.

The most dangerous elements are the subversive ones.

[alancalverd]

I don't think the Sulphur hexa fluoride in the grid switchgear poses much danger these highly active chemicals are tamed when they are formed into suitable molecules.

But now the ecofascists are claiming that SF6 must be banned as it is a zillion times more potent than cow farts as a greenhouse gas. You can't win.

[evan_au]

SF₆ must be banned

This is a pretty dense gas - how well would it mix into the stratosphere?

I heard that the main risk with SF₆ was that it tended to accumulate in low-lying areas, so you needed to carry a low-oxygen alarm and respirator with you.

[Bored chemist]

FFS!
What is it about SF6 that makes otherwise reasonable people- even scientists- forget basic science.

This is a pretty dense gas - how well would it mix into the stratosphere?

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch4/properties2.html

"Gases have three characteristic properties: (1) they are easy to compress, (2) they expand to fill their containers, and (3) they occupy far more space than the liquids or solids from which they form."

[Bored chemist]

ecofascists

And that's where people stop paying attention.

SF6 is about 24000 times more effective at trapping IR than CO2 (calculated over 100 years).
Methane is about 84 times more potent than CO2