Abundance of the chemical elements 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. The mass-abundance of the nine most abundant elements in the Earth's crust is approximately: oxygen 46%, silicon 28%, aluminum 8.2%,
The Tipping Point The Tipping Point The Tipping Point: How Little Things Can Make a Big Difference is the debut book by Malcolm Gladwell, first published by Little, Brown in 2000. Gladwell defines a tipping point as "the moment of critical mass, the threshold, the boiling point". The book seeks to explain and describe the "mysterious" sociological changes that mark everyday life. As Gladwell states: "Ideas and products and messages and behaviors spread like viruses do". The examples of such changes in his book include the rise in popularity and sales of Hush Puppies shoes in the mid-1990s and the steep drop in