Coal Tar. Tar derived from both coal and wood (e.g., juniper, pine) are both used for medicinal purposes. However, coal tar is the type used most commonly to treat psoriasis. Tar can help slow the rapid growth of skin cells and restore the skin's appearance. In addition, it can help reduce the inflammation, itching and scaling of psoriasis. Tar products can vary dramatically from brand to brand.
Quick Answer. The lightest element on the periodic table is hydrogen. The atomic weight of hydrogen is 1.00794 and the atomic number is 1. Hydrogen is the most abundant element on the periodic table with 75 percent of the mass of the universe consisting of hydrogen. Continue Reading.
At a given temperature and pressure, the density of a gas is proportional to its molecular weight. In theory, the next lightest gas after helium would be borane, BHâ (13.8 amu) but it exists as a minor component in equilibrium with its dimer, BâHâ (27.6 amu) and canât be obtained as a pure gas. The true next lightest gases would be methane, CHâ (16 amu), ammonia, NHâ (17 amu), hydrogen fluoride, HF (20 amu), and neon (20.2 amu). Because nitrogen, oxygen, and fluorine are all diatomic, their molecular weights are 28, 32, and 38 atomic mass units, respectively, and they are therefore denser than neon.