Big History: The Big Bang, Life on Earth, and the Rise of Humanity

Lecture 8: Threshold 3—Making Chemical Elements

through gold and lead, to uranium. Then they will be scattered throughout

nearby space.

In summary, it has taken three steps to create the chemical elements from

which we are constructed. Hydrogen and helium, the simplest atoms in

the periodic table, were created during the big bang. In their death throes,

medium to large stars create elements such as carbon (6 protons), nitrogen

(7 protons), oxygen (8 protons), silicon (14 protons), and up to iron (with

26 protons). As dying stars throw off their outer layers, these elements are

scattered through space, which is why, though not as common as hydrogen

and helium, these elements are more common than the other elements of

the periodic table. The remaining elements were manufactured and scattered

through space in supernova explosions. (If you’re wearing a gold ring, it was

forged in a supernova and is on very temporary loan to you!) The ¿ rst stars

provided the energy À ows and the chemical ingredients needed to make even

more complex entities such as our Earth. Ŷ

Brown, Big History, chap. 1.

Christian, Maps of Time, chap. 2.

Delsemme, Our Cosmic Origins, chap. 3.

Chaisson, Epic of Evolution, chap. 3.

Croswell, The Alchemy of the Heavens.

1. What were the three main stages in which the chemical elements
   were forged?


2. Why are chemical elements crucial to the emergence of new forms
   of complexity?

Essential Reading

Supplementary Reading

Questions to Consider