Chemical element universe's 94 naturally occurring chemical elements are thought to have been produced by at least four cosmic processes. Most of the hydrogen, helium and a very small quantity of lithiumin the universe was produced primordially in the first few minutes of the Big Bang. Other three recurrently occurring later processes are thought to have produced the remaining elements. Stellar nucleosynthesis, an ongoing process inside stars, produces all elements from carbon through iron in atomic number, but little lithium, beryllium, or boron. Elements heavier in atomic number than iron, as heavy as uranium and plutonium, are produced by explosive nucleosynthesis in
Period 6 element a massive extraterrestrial object caused the extinction of dinosaurs and many other species 66 million years ago. It is thought that the total amount of iridium in the planet Earth is much higher than that observed in crustal rocks, but as with other platinum group metals, the high density and tendency of iridium to bond with iron caused most iridium to descend below the crust when the planet was young and still molten. Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term "platina", which is