2 1.2% 1.4% titanium dioxide TiO 2 0.7% 1.4% phosphorus pentoxide P 2 O 5 0.2% 0.3% Total 99.6% 99.9% Size comparison of Earth and Uranus Chemical composition See also: Abundance of elements on Earth The mass of the Earth is approximately 5.98 × 10 24 kg. It is composed mostly