The are elements on the periodic table
When we first dig into soil, it's nice and soft.( Depending on what soil it is; usually topsoil)
But when we go deeper into it, there are rocks and the soil is harder. There is bedrock at the bottom, subsoil in the middle, and topsoil at the top, which is where we walk.
Based on its position in the periodic table, you can predict how many electrons it has, how many valence electrons, how many levels of electrons, and its atomic number and mass.
