00:00hello greeting welcome it's physical
00:04and today you will learn about the
00:06formation of light elements in the early
00:09called the big bang nucleosynthesis
00:28at the end of this video you should be
00:31how these light elements are formed
00:35to understand this lesson better let's
00:38the big bang theory big bang theory
00:42explains the primordial
00:44creation and expansion of space at the
00:48this is the most widely accepted theory
00:50that the vast universe
00:52grew out of something where all matter
00:55energy were compressed to infinite
00:57density and heated to trillions of
01:01a fraction second after the explosion
01:03the universe was filled with quarks
01:06that combined to form protons and
01:10moments later protons and neutrons
01:14matter began to take form light elements
01:17hydrogen helium lithium and beryllium
01:21formed through the process called big
01:23bang nucleosynthesis now what is the
01:26boundary of new synthesis
01:29nuclear synthesis refers to the process
01:32new atomic nuclei from pre-existing
01:35nucleus primarily protons
01:37and neutrons the vapour theory predicts
01:41that the early universe was a very hot
01:45too hot that even the particles of
01:48proton and neutron are destroyed
01:50during collision since big bang is an
01:55when the universe expands it cools
01:59one second after the explosion the
02:01temperature slowly decreases to a point
02:06for the protons and neutrons to combine
02:09and that is where the big bang nuclear
02:13as defined earlier nuclear synthesis
02:16occurs when protons and neutrons combine
02:18so when one proton combines with one
02:24the etheron an isotope of hydrogen is
02:27formed now remember this the identity of
02:31comes from the number of protons in its
02:35hydrogen has one proton helium has two
02:39lithium has three beryllium has four
02:42and so on this means that no elements or
02:46have the same number of protons so if
02:49you are going to look at the periodic
02:51the elements are arranged according to
02:53increasing number of protons
02:55and we call it atomic number we'll study
02:59this further in the next chapters
03:02when deity run combines with one neutron
03:05tripod is formed and this is still
03:08hydrogen since it has only one proton
03:12regardless of the number of neutrons in
03:15as you can see hydrogen has three
03:19we have proton since one proton can be
03:21regarded as the nucleus of a hydrogen
03:24the euthyrone with one proton and one
03:28triton with one proton and two neutrons
03:33they all have the same number of protons
03:36but differ in the number of neutron
03:38and that is how we define an isotope
03:43two particles of deityron can combine to
03:46helium atom with two protons and two
03:50already triton is bombarded with a
03:54helium is also formed so there are many
03:56ways to form helium atom through
03:59the collision of hydrogen isotopes a
04:01helium ion is bombarded with a triton
04:04the nuclei now have three protons
04:08and four neutrons what do you think is
04:13correct lithium how about when two
04:18how many protons and neutrons are in the
04:23yes there are four protons and four
04:27what about the element what element is
04:30formed correct we have beryllium
04:35since lithium and beryllium are heavier
04:38it requires a lot of energies to form
04:40that is the reason why there are only a
04:43portion of these elements in the
04:45compared to hydrogen and helium the
04:48universe is said to contain 75
04:51hydrogen and 25 percent helium
04:55light from distant galaxies are from
04:59which emit spectra of a particular
05:02primarily hydrogen and helium
05:06now since the universe continues to
05:09minutes after the explosion the
05:11temperature continuously drops
05:14making the particles unable to combine
05:17due to the insufficient amount of
05:21particles bounces back during collision
05:24and no more elements are formed
05:27so that is how light elements are formed
05:30in the early universe through the
05:33big bang nuclear synthesis in our next
05:36lesson we will discuss the formation of
05:40stellar evolution for the stellar
05:43and that ends our lesson i hope you
05:45learned something today
05:46thank you for watching welcome last part
05:52one two three go and that ends our
05:56lesson i hope you learned something
05:58thank you for watching
06:01that ends hourly one two three go
06:04and that ends our one two three go and
06:07that ends our lesson i hope you learned
06:10thank you for watching
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