Varied Planet composition

[Vindhya]

If all heavenly bodies arose from a unit mass after big bang why the planets in our solar system differ in their composition?

[cameron marical]

different atoms created by different amounts of energy at one spot turning into mass?

just a guess.

[D H]

You are asking two distinct questions, Vindhya: How did the elements form, and why do planets have different compositions?

 

How the elements formed is the subject of nucleosynthesis. Google that term. I have denoted some key terms and phrases in bold. Google these for more information.

 

The big bang only created the lightest of elements: hydrogen, helium, and lithium. Stars produce heavier elements by means of fusion, up to and including iron (and only very massive stars can produce iron). Iron is the most stable of all nuclei. Getting past iron requires a vert special circumstance: A supernova. So, three very distinct processes are needed to explain the elements: big bang nucleosynthesis, stellar nucleosynthesis, and supernova nucleosynthesis.

 

How the planets formed and why their compositions differ is the subject of the nebular hypothesis. Where and when a planet formed are the key factors that lead to the composition of the planet. The protoplanetary disk from which the planets formed had a temperature gradient, warmest near the newly-forming star. Get close enough to the protostar and things like water, ammonia, and methane are gases rather than solids. Outside some radius (the frost or ice line), the planetesimals could include stuff like water, ammonia, and methane ice. Inside the frost line they couldn't. The planets outside the frost line had more stuff (a lot more stuff) to work with. The outer planets could and did get huge, and did do so rather quickly. Inside the frost line, only rocky and metallic materials could coallesce to form planetesimals.