The document discusses the basic structure of atoms and elements. Atoms are made up of protons, neutrons, and electrons. The nucleus contains protons and neutrons at the center, surrounded by electrons. Elements are pure substances made of only one type of atom that cannot be broken down further. There are over 118 known elements, with 92 existing naturally and some being man-made, and most elements exist as solids. Elements are represented by chemical symbols like C for carbon and Fe for iron.