Period 2 element two make up all natural occurrence of lithium on Earth, although further isotopes have been synthesized. In ionic compounds, lithium loses an electron to become positively charged, forming the cation Li. Lithium is the first alkali metal in the periodic table, and the first metal of any kind in the periodic table. At standard temperature and pressure, lithium is a soft, silver-white, highly reactive metal. With a density of 0.564 g·cm, lithium is the lightest metal and the least dense solid element. Lithium is one of the few elements synthesized in the Big Bang, making it a primordial element. Lithium
Eckart conditions better understanding of the Eckart frame it may be useful to remark that it becomes a principal axes frame in the case that the molecule is a rigid rotor, that is, when all "N" displacement vectors are zero. The "N" position vectors formula_11 of the nuclei constitute a 3"N" dimensional linear space R: the "configuration space". The Eckart conditions give an orthogonal direct sum decomposition of this space The elements of the 3"N"-6 dimensional subspace R are referred to as "internal coordinates", because they are invariant under overall translation and rotation of the molecule and, thus, depend only on the