To first order , the Earth as well as other rocky planets in the Solar System and rocky exoplanets orbiting other stars , are refractory pieces of the stellar nebula out of which they formed .
To estimate the chemical composition of rocky exoplanets based on their stellar hosts ’ elemental abundances , we need a better understanding of the devolatilization that produced the Earth .
To quantify the chemical relationships between the Earth , the Sun and other bodies in the Solar System , the elemental abundances of the bulk Earth are required .
The key to comparing Earth ’ s composition with those of other objects is to have a determination of the bulk composition with an appropriate estimate of uncertainties .
Here we present concordance estimates ( with uncertainties ) of the elemental abundances of the bulk Earth , which can be used in such studies .
First we compile , combine and renormalize a large set of heterogeneous literature values of the primitive mantle ( PM ) and of the core .
We then integrate standard radial density profiles of the Earth and renormalize them to the current best estimate for the mass of the Earth .
Using estimates of the uncertainties in i ) the density profiles , ii ) the core-mantle boundary and iii ) the inner core boundary , we employ standard error propagation to obtain a core mass fraction of 32.5 \pm 0.3 wt % .
Our bulk Earth abundances are the weighted sum of our concordance core abundances and concordance PM abundances .
Unlike previous efforts , the uncertainty on the core mass fraction is propagated to the uncertainties on the bulk Earth elemental abundances .
Our concordance estimates for the abundances of Mg , Sn , Br , B , Cd and Be are significantly lower than previous estimates of the bulk Earth .
Our concordance estimates for the abundances of Na , K , Cl , Zn , Sr , F , Ga , Rb , Nb , Gd , Ta , He , Ar , and Kr are significantly higher .
The uncertainties on our elemental abundances usefully calibrate the unresolved discrepancies between standard Earth models under various geochemical and geophysical assumptions .