• Question: What elements is the most dangerous if the would be combined?

    Asked by 245drud47 to Sinead, Mark, Florence, Anne, Neil on 6 Nov 2015.
    • Photo: Mark Collins

      Mark Collins answered on 6 Nov 2015:

      There are so so many elements that this could apply to but thankfully so many chemists are responsible and we take our own safety and that of our colleagues and the environment and would never combine chemicals if we knew it would be dangerous to human health or the environment.

    • Photo: Florence McCarthy

      Florence McCarthy answered on 7 Nov 2015:

      Some of the most simple elements are explosive – rocket fuel consists of liquid hydrogen and liquid oxygen.

    • Photo: Neil Day

      Neil Day answered on 8 Nov 2015:

      There are many elements that are safe when on their own but when combined with another element are extremely dangerous. If you look up the periodic table, the most dangerous elements are generally grouped together; on the left hand column which are the alkalines; these elements are really eager to loose an electron. On the column one in from the right, are the halogens; these guys are really eager to receive an electron. You might see that there is a certain chemical attraction in the way these elements are grouped!
      All the alkaline metals will react violently with water (For an example see what happens to Caesium when dropped into water; https://www.youtube.com/watch?v=D4pQz3TC0Jo). Basically Caesium wants to displace hydrogen and give it’s ‘extra’ electron away.
      In a similar manner, when halogens are combined with hydrogen they form acids. one of the most dangerous is hydrofluoric acid (hydrogen and fluorine = HF).
      In the early part of my career I had to work with HF and we had to undertake a lot of special training so we could use it safely and know what to do if we were exposed to it.

    • Photo: Sinead Balgobin

      Sinead Balgobin answered on 9 Nov 2015:

      It depends what you mean by dangerous… There are lots of elements that can cause explosions when combined, and humans (being the destructive lot that we are) have discovered and developed a lot of them. Florence and Neil give a lot of good examples, and on Youtube “The Periodic Table of Videos” does a good job of showing them off (they have made videos for every element of the periodic table).

      There are also chemicals that are bad for you health in other ways; chlorine gas, acids like HF mentioned by Neil, and even everyday molecules made of just carbon, hydrogen, maybe oxygen and nitrogen. Being a chemist means we have to take a lot of responsibility and caution with what we do- we should always aim to keep people safe.

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