The Formation of the Light Elements in the Beginning

The video stated that a (a)   is an idea of or belief about something arrived through speculation or conjecture. It is also defined as a scientific principle to explain a phenomena.

This theory proposes that the universe was once extremely compact/dense, and hot. Then there was a sudden expansion that occurred billions of years ago, and since then the universe has been expanding and cooling.

(a)  

The video mentioned regarding the lightest elements. Select from the following the lightest elements.

• Hydrogen

• Helium

• Lithium

• Beryllium

• Sodium

The video referred to the (a)   as elementary particles that combine to form protons and neutrons.

In the video, when the conditions allowed, the protons and neutron combined as (a)   .

The video describes (a)   as the process that creates new atomic nucleus from protons and neutrons.

During nucleosynthesis, the extremely high energy and temperature allowed the combination of neutrons and protons to form certain species of atomic nuclei in a process called (a)   .

When universe had cooled enough, negatively charged electrons combined with positive nuclei to form stable (a)   .

During the proton-proton chain reactions, 2 Hydrogen can form a (a)   - a Hydrogen isotope with 1 proton and 1 neutron in the nucleus.

It is the most abundant element in the universe. The video mentioned that it is close to 75 percent of the ordinary matter in the universe by mass.

(a)