How do atoms kind? – The Hindu
Richard Feynman, a well-known theoretical physicist who received the Nobel Prize, mentioned that if he may move on just one piece of scientific info to future generations, it could be that every one issues are manufactured from atoms.
Understanding how atoms kind is a basic and necessary query, since they make up the whole lot with mass.
The query of the place atoms come from requires a variety of physics to be answered fully – and even then, physicists like me solely have good guesses to elucidate how some atoms are fashioned.
What’s an atom?
An atom consists of a heavy centre, known as the nucleus, manufactured from particles known as protons and neutrons. An atom has lighter particles known as electrons that you can imagine as orbiting across the nucleus.
The electrons every carry one unit of detrimental cost, the protons every carry one unit of optimistic cost, and the neutrons haven’t any cost. An atom has the identical variety of protons as electrons, so it’s impartial − it has no general cost.
Now, many of the atoms within the universe are the 2 easiest sorts: hydrogen, which has one proton, zero neutrons and one electron; and helium, which has two protons, two neutrons and two electrons. After all, on Earth there are many atoms moreover these which are simply as frequent, corresponding to carbon and oxygen, however I’ll speak about these quickly.
A component is what scientists name a gaggle of atoms which are all the identical, as a result of all of them have the identical variety of protons.
When did the primary atoms kind?
Many of the universe’s hydrogen and helium atoms fashioned round 400,000 years after the Huge Bang, which is the identify for when scientists assume the universe started, about 14 billion years in the past.
Why did they kind at the moment? Astronomers know from observing distant exploding stars that the scale of the universe has been getting larger because the Huge Bang. When the hydrogen and helium atoms first fashioned, the universe was about 1,000 instances smaller than it’s now.
And based mostly on their understanding of physics, scientists imagine that the universe was a lot hotter when it was smaller.
Earlier than this time, the electrons had an excessive amount of vitality to settle into orbits across the hydrogen and helium nuclei. So, the hydrogen and helium atoms may kind solely as soon as the universe cooled right down to one thing like 2,760 levels C. For historic causes, this course of is misleadingly known as recombination − mixture can be extra descriptive.
The helium and deuterium − a heavier type of hydrogen − nuclei fashioned even earlier, just some minutes after the Huge Bang, when the temperature was above 556 million C. Protons and neutrons can collide and kind nuclei like these solely at very excessive temperatures.
Scientists imagine that the majority the strange matter within the universe is manufactured from about 90% hydrogen atoms and eight% helium atoms.
How do extra large atoms kind?
So, the hydrogen and helium atoms fashioned throughout recombination, when the cooler temperature allowed electrons to fall into orbits. However you, I and nearly the whole lot on Earth is manufactured from many extra large atoms than simply hydrogen and helium. How had been these atoms made?
The stunning reply is that extra large atoms are made in stars. To make atoms with a number of protons and neutrons caught collectively within the nucleus requires the kind of high-energy collisions that happen in highly regarded locations. The vitality wanted to kind a heavier nucleus must be massive sufficient to beat the repulsive electrical drive that optimistic fees, like two protons, really feel with one another.
Protons and neutrons even have one other property – type of like a distinct sort of cost – that’s sturdy sufficient to bind them collectively as soon as they can get very shut collectively. This property is known as the sturdy drive, and the method that sticks these particles collectively is known as fusion.
Scientists imagine that many of the parts from carbon as much as iron are fused in stars heavier than our Solar, the place the temperature can exceed 556 million C – the identical temperature that the universe was when it was just some minutes previous.
However even in sizzling stars, parts heavier than iron and nickel received’t kind. These require further vitality, as a result of the heavier parts can extra simply break into items.
In a dramatic occasion known as a supernova, the interior core of a heavy star all of the sudden collapses after it runs out of gas to burn. In the course of the highly effective explosion this collapse triggers, parts which are heavier than iron can kind and get ejected out into the universe.
Astronomers are nonetheless determining the main points of different incredible stellar occasions that kind bigger atoms. For instance, colliding neutron stars can launch monumental quantities of vitality – and parts corresponding to gold – on their option to forming black holes.
Understanding how atoms are made simply requires studying just a little common relativity, plus some nuclear, particle and atomic physics. However to complicate issues, there may be different stuff within the universe that doesn’t look like constituted of regular atoms in any respect, known as darkish matter. Scientists are investigating what darkish matter is and the way it would possibly kind.
Stephen L. Levy Affiliate Professor of Physics and Utilized Physics and Astronomy, Binghamton College, State College of New York. This text is republished from The Dialog.
Printed – July 09, 2025 06:00 am IST
