This is a topic i've always been interested in, but also always a littl ignorant of it, but the time seems to be right for us to watch this space.
The heaviest elements found in nature are uranium, neptunium and plutonium. But these aren't the heaviest elements found.
What defines an element is it's proton number; literally the number of protons in their nucleii. The simplest element is hydrogen which has a single proton, and, uniquely, no neutrons. After hydrogen we have helium which usually has 2 protons and 2 neutrons, although sometimes a helium atom exists with only one neutron. This is an example of an isotope, which is an atom with the same amount of protons and a different amount of neutrons. Some elements have more than one stable isotope. For instance bromine has two: bromine-81 and bromine-79. the numbers relate to the mass of the isotopes, which is the sum of protons and neutrons, so bromine 81 has 35 protons and 46 neutrons.
The reason that nucleii hold together is that there is a force between particles, known as the strong nuclear force, which can overcome the repulsion between the positively charged protons. that's why you need a few neutrons as well as protons to hold everything together. Neutrons add to the strong nuclear force but don't add to the repulsive forces between the protons.
So when you get to elements as large as, for instance, seaborgium (element 106, which, when i first studied chemistry, was known only as unnilhexium), you need a lot of neutrons. seaborgium has 106 protons and 165 neutrons, in its most stable isotope.
Now when I say stable, i mean more stable than the other isotopes. Seaborgium-271 has a half-life of 1.9 minutes, which means if i have a gram of seaborgium, 1.9 minutes later i'll only have 0.5 grams left, because it will have decayed, probably into rutherfordium, element 104. As we head further up the periodic table, the elements generally (but not always) get less stable.
the interesting thing about superheavy elements is that some of the heaviest elements are more stable than you might imagine. Roentgenium, element 111, has a half-life of 3.6 seconds. Now that's fairly short, but some scientists would have predicted it didn't exist for more than a femtosecond.
discoveries such as these made nuclear physicists invent a new kind of physics which helped explain these obsevations, and predict new elements. Seaborg, a scientist who discovered more elements than any other, predicted a "map" of stability. Basically it's a graph of the number of protons, versus the number of neutrons in each element. Each square on this map represents a possible isotope, and is shown as a bar, representing the length of the half life of the isotope, or as a blank, representing an isotope which is unstable.
The interesting thing about this map is that it shows us that there may be some so-far undiscovered isotopes which are surprisingly stable. One such isotope is the fabled 114th element, which is said to be particularly stable. Particularly, the isotope 298-UUq might be stable enough for people to actually see and hold in their hand.
Element 114 has already been isolated, but not the isotope the scientists are hoping for. the most stable isotope yet found is 289-UUq, which has a half-life of 2.6 seconds. It is thought that 298-UUq might have a half-life measurable in years.
Even more interesting is that there are more than one of these "maps" based on slightly different science. And some of these maps predict that element 122 might be particularly stable. recently, a group from a middle-eastern university claim that they discovered element 122 in a sample of thorium (LINK). If their claim is held to be true (the paper is not yet peer-reviewed), then it might prove that there are more elements to be found in the far reaches of the map.
So if element 122 does exist... where does it belong on the periodic table? examine the periodic table below and think on the question for a while:
If you count up the proton numbers, you'll see that the row is finished at 118. So perhaps 122 goes on the row beneath? Well yes, but there's more to it than that. In fact, element 122 would be the first ever discovered "g-block" element. If the claim holds true, the entire periodic table will have to be re-organized to show it in its correct position. Wikipedia contains a proposed new periodic table (LINK).
Someone recently asked me what was the point of this stuff... in his words "how many mouths will it feed?". I thought about it for a while and then remembered what Faraday said when he was asked what use his electricity might have:
"what use is a newborn baby?"
The heaviest elements found in nature are uranium, neptunium and plutonium. But these aren't the heaviest elements found.
What defines an element is it's proton number; literally the number of protons in their nucleii. The simplest element is hydrogen which has a single proton, and, uniquely, no neutrons. After hydrogen we have helium which usually has 2 protons and 2 neutrons, although sometimes a helium atom exists with only one neutron. This is an example of an isotope, which is an atom with the same amount of protons and a different amount of neutrons. Some elements have more than one stable isotope. For instance bromine has two: bromine-81 and bromine-79. the numbers relate to the mass of the isotopes, which is the sum of protons and neutrons, so bromine 81 has 35 protons and 46 neutrons.
The reason that nucleii hold together is that there is a force between particles, known as the strong nuclear force, which can overcome the repulsion between the positively charged protons. that's why you need a few neutrons as well as protons to hold everything together. Neutrons add to the strong nuclear force but don't add to the repulsive forces between the protons.
So when you get to elements as large as, for instance, seaborgium (element 106, which, when i first studied chemistry, was known only as unnilhexium), you need a lot of neutrons. seaborgium has 106 protons and 165 neutrons, in its most stable isotope.
Now when I say stable, i mean more stable than the other isotopes. Seaborgium-271 has a half-life of 1.9 minutes, which means if i have a gram of seaborgium, 1.9 minutes later i'll only have 0.5 grams left, because it will have decayed, probably into rutherfordium, element 104. As we head further up the periodic table, the elements generally (but not always) get less stable.
the interesting thing about superheavy elements is that some of the heaviest elements are more stable than you might imagine. Roentgenium, element 111, has a half-life of 3.6 seconds. Now that's fairly short, but some scientists would have predicted it didn't exist for more than a femtosecond.
discoveries such as these made nuclear physicists invent a new kind of physics which helped explain these obsevations, and predict new elements. Seaborg, a scientist who discovered more elements than any other, predicted a "map" of stability. Basically it's a graph of the number of protons, versus the number of neutrons in each element. Each square on this map represents a possible isotope, and is shown as a bar, representing the length of the half life of the isotope, or as a blank, representing an isotope which is unstable.
The interesting thing about this map is that it shows us that there may be some so-far undiscovered isotopes which are surprisingly stable. One such isotope is the fabled 114th element, which is said to be particularly stable. Particularly, the isotope 298-UUq might be stable enough for people to actually see and hold in their hand.
Element 114 has already been isolated, but not the isotope the scientists are hoping for. the most stable isotope yet found is 289-UUq, which has a half-life of 2.6 seconds. It is thought that 298-UUq might have a half-life measurable in years.
Even more interesting is that there are more than one of these "maps" based on slightly different science. And some of these maps predict that element 122 might be particularly stable. recently, a group from a middle-eastern university claim that they discovered element 122 in a sample of thorium (LINK). If their claim is held to be true (the paper is not yet peer-reviewed), then it might prove that there are more elements to be found in the far reaches of the map.
So if element 122 does exist... where does it belong on the periodic table? examine the periodic table below and think on the question for a while:
If you count up the proton numbers, you'll see that the row is finished at 118. So perhaps 122 goes on the row beneath? Well yes, but there's more to it than that. In fact, element 122 would be the first ever discovered "g-block" element. If the claim holds true, the entire periodic table will have to be re-organized to show it in its correct position. Wikipedia contains a proposed new periodic table (LINK).
Someone recently asked me what was the point of this stuff... in his words "how many mouths will it feed?". I thought about it for a while and then remembered what Faraday said when he was asked what use his electricity might have:
"what use is a newborn baby?"
