Skilfully crafted 35 mm slides on the topic of atoms, fit for a Kodaslide Home Projector that was first created in 1937. By comparison, atoms were created 13.7 billion years ago, right after the Big Bang. Atoms are the basic units of matter and the defining structure of elements. They are made up of three particles: protons, neutrons and electrons, which are composed of even smaller particles, such as quarks. After the Big Bang, quarks came together to form protons and neutrons, and these particles combined into nuclei. This all took place within the first few minutes of the universe’s existence, according to CERN.