English: Oxygen atoms (shown as red spheres) and hydrogen atoms (shown as white spheres) either occur as elements (left) or react to form the compound water (right). The periodic table (background) provides a framework to predict structure and reactivity, e.g. why two atoms of hydrogen combine with one atom of oxygen. This image shows space-filling models of dihydrogen, dioxygen and water molecules, illustrating the formation of water from the elements. The background shows the periodic table of elements, with the elements hydrogen and oxygen boxed. The background is based on a screen shot of the article Platinum in the English wikipedia. The molecules were rendered with the free software jmol, using the First glance in Jmol user interface. The graphics software gimp was used to assemble the image.