Science Forums 2

[HydrogenBond]

One naive assumption about the earth's make-up during formation has to do with heavier materials sinking and lighter materials floating. This is based on the assumption of inert materials without chemical interactivity.

For example, if we drop salt in water, it will sink due to the density differences. But as the salt dissolves, the heavier salt will be found on the top as well as the bottom of the glass. Hydrogen is very light and will float out to space in we assume inert. But when it reacts with oxygen, it becomes H2O. Now H stays put.

If you look at the assumed composition of the earth, Fe and O are the two primary atoms.
To get pure iron for the core, we would need a source of electrons or a reducing agent to avoid the O collecting any electrons from iron. The Fe and O is about 55% of the mass of the earth in roughly equal mass parts but not equal atoms counts. Oxygen takes electrons and doesn't give them up easily. Mg and Si make up about 28% of the weight with both oxidized. What type of materials would need to be generated that are deficient of elections so the iron remain pure iron and the oxygen able to satisfy its chemical potential for extra electrons for -1 or -2?

We can do this the other way. With pure iron in the core, there are not enough electrons on the earth for all the oxygen on the earth, unless we can point to a large external source of electron deficient materials that don't contain oxygen (if they contain O, they gave electron to this O and not the earth). If the oxygen atoms on earth are not full of extra electrons (-1 or -2), more oxygen would have to be in the form of O2, H2O and other covalently bonded molecules, where the oxygen can share electrons and lower the electron requirement. But composition data does not support this. So what we have assumed is the iron can remain with all its electrons at the same time O can remain starved for electrons, even when there are 2-3 times the number of O atoms to Fe atoms each wanting 1 or 2 extra electrons.

This adds up to an iron oxide core, unless one can show where all the electrons for the O of the earth came from, given the composition of the earth? One will have to end up with a large source of bare + charge, without electron accompaniment, since oxygen goes for -1 or -2.