<P> A further observed peculiarity is the jagged alternation between relative abundance and scarcity of adjacent atomic numbers in the elemental abundance curve, and a similar pattern of energy levels in the nuclear binding energy curve . This alternation is caused by the higher relative binding energy (corresponding to relative stability) of even atomic numbers compared with odd atomic numbers and is explained by the Pauli Exclusion Principle . The semi-empirical mass formula (SEMF), also called Weizsäcker's formula or the Bethe - Weizsäcker mass formula, gives a theoretical explanation of the overall shape of the curve of nuclear binding energy . </P> <P> The Earth formed from the same cloud of matter that formed the Sun, but the planets acquired different compositions during the formation and evolution of the solar system . In turn, the natural history of the Earth caused parts of this planet to have differing concentrations of the elements . </P> <P> The mass of the Earth is approximately 5.98 × 10 kg . In bulk, by mass, it is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%); with the remaining 1.2% consisting of trace amounts of other elements . </P> <P> The bulk composition of the Earth by elemental - mass is roughly similar to the gross composition of the solar system, with the major differences being that Earth is missing a great deal of the volatile elements hydrogen, helium, neon, and nitrogen, as well as carbon which has been lost as volatile hydrocarbons . The remaining elemental composition is roughly typical of the "rocky" inner planets, which formed in the thermal zone where solar heat drove volatile compounds into space . The Earth retains oxygen as the second - largest component of its mass (and largest atomic - fraction), mainly from this element being retained in silicate minerals which have a very high melting point and low vapor pressure . </P>

What is the most abundant chemical on earth