In one mole, there are 6.022 x 10 23 atoms. Here's another way: there are 6.022 x 10 23 atoms of carbon in 12 grams of carbon-12. Let's say that real clearly: one mole of ANYTHING contains 6.022 x 10 23 entities. The word entities is simply a generic word.
Shadow zone. A seismic shadow zone is an area of the Earth's surface where seismographs cannot detect an earthquake after its seismic waves have passed through the Earth. When an earthquake occurs, seismic waves radiate out spherically from the earthquake's focus.
For the usable light source, see Shadow Orb (item). A Shadow Orb is a floating purple sphere, found deep in the Chasms of the Corruption. Destroying at least three of these orbs (in a single world) will usually be a crucial step in game advancement. This can be done using any Hammer, or Bombs / Dynamite.