Question

Arrange the events of the big bang in sequential order. The first neutral atoms form. The universe is transparent. Atomic nuclei form. Hydrogen fuses into helium. The universe comes into existence as a single point. Gases form that will later go on to shape the stars and galaxies. The universe begins expanding, and nuclear forces develop.

Answer 1

1. The universe comes into existence as a single point.

It is considered that the universe was created as a very hot and dense and as a single point in space.

2.  The universe begins expanding, and nuclear forces develop.

The four fundamental forces: electromagnetism, weak nuclear force, strong nuclear force and gravity were formed.

3. Atomic nuclei form.

Universe started to expand, became cooler and less dense. Protons and neutrons collided to make deuterium - an isotope of hydrogen

4. Hydrogen fuses into helium.  

Formed deuterium atoms combined to form helium.

5. The first neutral atoms form  

When matter in the universe cooled enough, electrons combined with nuclei to form neutral atoms

6. The universe is transparent.

In the phase "recombination," the absorption of free electrons caused the universe to become transparent.

7. Gases form that will later go on to shape the stars and galaxies.  

This is the phase of reionization, where gases collapsed enough to form the very first stars and galaxies.  

Answer 2

Below are named the relevant Big Bang periods that contain the events in the question.

The Planck Epoch (or Planck Era) from 0 to $10^{-43}$ seconds is the earliest period of time our current physics can describe, although in extremely general terms.

1. The universe comes into existence as a single point.

The Inflationary Epoch from $10^{-36}$ to $10^{-32}$ seconds. The universe undergoes through cosmic inflation, an extremely rapid exponential expansion due to the separation of the strong nuclear force.

2. The universe begins expanding, and nuclear forces develop.

Nucleosynthesis, from 3 minutes to 20 minutes: Due to the falling temperature of the universe, atomic nuclei can begin to form into the elements of hydrogen, helim and lithium.

3. Atomic nuclei form and 4. Hydrogen fuses into helium.

After 20 minutes, the temperature has decreased sufficiently to inhibit further nuclear fusion.

5. Gases form that will later go on to shape the stars and galaxies.

The Recombination/Decoupling, , from 240,000 to 300,000 years:

6. The first neutral atoms form - as the Universe's temperature decreases to that of our Sun's surface together with its density, electrons are captured/"recombined" with ionized hydrogen and helium atoms. Thus, their electric charge is neutralized and the first neutral atoms form.

7. The universe is transparent - due to the electrons being bound, the universe becomes transparent to light. It is the earliest period of the universe we can currently observe with out telescopes.