The element has a half-life of 1 billion times the life of the universe

A series of stars have long since disappeared, but the bismuth element will still exist and continue to decay.

When you ask a high school student that the element is stable, does not contain the heaviest radiation, the student will answer you "lead", and my family members will have the phrase "Heavy as lead" ! But if you ask a chemist, he will glance at the periodic table and answer that it is "Bismuth". The fact of this incident is more complex and interesting than you think.

The chemical researcher was right (otherwise, what did they do for the chemical researcher?). All elements heavier than bismuth (element 83) have no stable isotopes, and very few have a long decay process, such as thorium and uranium.

Bismuth element, compared to a 1cm cube.

But is bismuth really stable?Bismuth in nature is made up of bismuth-209 isotopes, the isotopes whose atoms contain 83 protons and 126 neutrons. At present, the atomic structure has been well studied and we have a better understanding of them, since we can calculate the nucleus of bismuth-209 with a high energy state.

According to quantum physics, the alpha decay of bismuth-209 does not violate the law of energy conservation or any other law, so it is considered completely possible, but we have not yet witnessed it. what happened

Until 2003, a group of scientists in France published a new study of bismuth decay. By direct detection of alpha particles during bismuth-209 isotope decay, they were able to calculate the half-life of bismuth-209 as 1.9x1019.

It sounds long, but how long is it really? In comparison, our cylinder only had 1.38x1010 years old (since the Big Bang until now). So that means the half-life of bismuth-209 is nearly 1 billion times (109) the life of the universe.

Also short!

Big Bang explosion.

Based on our understanding of astronomy, as well as the formation of stars in the universe, all the stars will die in about 1014 years. So you have to wait a long time before the bismuth atom in the other Pepto-Bismol stomach medicine decays. Yes, bismuth is used in making this stomach medicine, and that "shelf" label is not really accurate.

So what will the universe be like in 1019 years?

Before the last stars faded to 1014 years, all the galaxies in the Local Group ( The Milky Way - The Milky Way) will merge. into a giant galaxy. If our current astronomical document survives until then, would astronomers believe that the universe had more galaxies then?

All galaxies in the Local Galaxy Group will merge into a giant galaxy.

By the time of 10 ¹⁵ years, planets orbiting the stars' orbits would have been fired from their inherent orbit. And even after 10,000 times that time, half of the bismuth still exists.

Take a little calculation, the bismuth decay time is calculated by the following formula:

In which, t1 / 2 is the half-life, λ is the decay constant, τ is the current time, N is the number of particles in the sample, and A is the number of decay per unit of time ( use time units similar to semi-decay elements.

Suppose, we have a bismuth block weighing one gram with a half centimeter diameter. We can calculate that the atomic mass in this bismuth block is 2.9x1021. Based on the above formula, we obtain an average decay rate of bismuth of 105 molecules per year (every molecule / day and a half).

BUT, this is just alpha decay. Alpha particles have very small penetrating power, they cannot penetrate the outer layer of heavy elements like bismuth. Therefore, when decaying, only surface molecules can escape, the rest will be locked inside.

Alpha decay will produce alpha particles separated from the nucleus.

Back to the first question, is it true that "lead" is the heaviest STABLE element in the periodic table?

Actually, it is still not true. Natural lead is made up of 4 isotopes: lead-204, lead-205, lead-207 and lead-208, with only-208 isotopes accounting for more than half. From the calculation of energy to make nuclear chemists suspect that bismuth is a bit radioactive, each nucleus of the other isotopes will also have a very long half-life. But through testing, scientists have never discovered the same thing that happens with bismuth.

When considering the slightly radioactive elements, bismuth is still not the champion.

But even so, when considering slightly radioactive elements, bismuth is still not the champion.Barium-130 decays into xenon-130 through decay from 0.5 to 2.7x1021 years, 100 times more than bismuth. And even, tellurium-128 decays into xenon-128 and must go through a 2.2x1024 year demolition process, this is the champion . With a half-life of 100,000 times longer than bismuth, and 160 million billion years of space, it's not hard to wear a crown, tellurium-128. Imagine, you have a gram of tellurium-128 (very expensive to synthesize, but no one has taxed the imagination), you will see it decay for the first time after 674 years.

According to another particle theory, protons and other elements must also decay. Experiments have shown that IF as protons decay, the time it takes for them to decay will be 1033 years, 50 million billion times more bismuth and 72 million billion times greater than the life of the universe.

What will you do while waiting for the proton to decay?A few walks around the universe to wait might seem logical.

And finally, 22 minutes is the shortest half-life, francium , its No. 87 element with its francium-223 isotope, 22 minutes is a pretty modest number compared to dozens of monsters. . This element was discovered in 1939, the last natural radioactive element was found, the latter elements were synthesized by humans. At all times, the amount of francium in the Earth's crust is estimated to be 20-30 grams. All materials from hydrogen to californium (element 98) are found in nature, almost all ejection elements. Radiation is detected by radioactive synthesis, but is later found in natural uranium ore.

There is a difference between that "element found in nature" and that " basic element" . Of the 98 elements found in nature, only 84 of them have atoms that existed naturally since the formation of the Solar System. Among them, 80 elements are stable and four of them are radioactive (bismuth, thorium, uranium, and plutonium).