Inorganic Chemistry/Atomic Structure

From Big Bang to Atoms

According to the Big Bang model, the universe expanded from an extremely dense and hot state and continues to expand today. A common analogy explains that space itself is expanding, carrying galaxies with it, like spots on an inflating balloon. The graphic scheme above is an artist's concept illustrating the expansion of a portion of a flat universe.

Big Bang, a great explosion that happened around 13.75 ± 0.11 billion years ago , is thought to create our universe. The idea is based on the observation that our universe is expanding, so it was probably a single point at some time in the past if we trace back.

At about 10^-6 seconds after the explosion, quarks and gluons combined to form baryons such as protons and neutrons, while anti-quarks and anti-gluons formed anti-protons and anti-neutrons. A small excess of quarks and gluons over their anti-particles led to a small excess of baryons over anti-baryons. Latter, the universe cooled to a level that it could not produce gluons, quarks, anti-gluons and anti-quarks. This led to a dramatic decrease in the universe mass: matter and anti-matter 'eats' each other, left only 1 of 10¹⁰ protons and neutrons survive and none of their anti-particles. That's why the universe now is a matter environment, not an anti-matter one :)

At one second afther the explosion, same thing happened to electrons and positrons (positrons are anti-electrons)

A few minutes after the explosion, the temperature was about 10⁹ K. The energy was still so high. Protons and neutrons didn't combine yet. When the universe got cooler, the strong force (a powerful but short-range force) got advantage, combined protons and neutrons together, formed nuclei. After 379,000 years, electromagnetic force (a weak but long-range force) got advantage, making electrons first attached to nuclei. The first atom was born, consisting of a nuclei (protons, neutrons) and one or more electrons.