Transcript: The cosmic abundance of different elements in the periodic table is a fundamental property of the universe that astronomers have successfully explained. The most abundant elements, hydrogen and helium, three quarters hydrogen and one quarter helium by mass, can only be explained when we understand the big bang. Helium was created in the first few minutes of the universe itself. Almost all the heavier elements come from nucleosynthesis within stars. The features of a graph of cosmic abundance versus atomic number show that after hydrogen and helium there’s a deep hole in abundance. Boron and beryllium are extremely rare elements because the decay prohibits them from being built up rapidly. There’s then a peak, carbon, nitrogen, and oxygen, the life elements, at abundances of 10-4 relative to hydrogen, then a slow decline, elements like magnesium and silicon at an abundance of 10-5 relative to hydrogen, and the pattern of elements show a sawtooth pattern every two in atomic number representing the addition of a helium nucleus in the way that the elements are built up. Then follows the iron peak, iron the most stable element, followed by a rapid fall down to abundances of only 10-9 or 10-10, silver and tin are at abundances of 10-11 , and then slow decline to the heaviest elements of all; gold has an abundance of 10-12 relative to hydrogen.