realize that elements of the periodic table exists in different standard states or sometimes called natural states. When it comes to the natural world, we're going to say here at room temperature, which is approximately 25 degrees Celsius and standard pressure, which is approximately one atmosphere elements exist as either solids, liquids or gasses. So for a quick review on the periodic table, what we have here in red are the elements that exist as gasses. Now some of them are mono atomic in terms of the noble gasses from helium all the way down to radar. But other gasses exist in a di atomic form where there are two of them combined together. This includes hydrogen, which is H2, nitrogen, which is end to oxygen, which is 02 F two for flooring and cl two for chlorine, then we have a few elements that can exist in the liquid phase. This includes bombing, which is also die atomic and mercury, which is mono atomic. A vast majority of the other elements on the periodic table in their natural state or standard states exist in the solid form as mono atomic. And then here we have in the bottom row these that aren't solids, liquids or gasses. These have been formed within laboratory or because of their high atomic masses are very unstable. So they don't come along with a phase at standard room temperature or pressure. Now remember in terms of these three phases in a solid, the molecules are fairly tight packed together in a liquid. They're more free to move around one another and then gasses, they're greatly spread apart. So just keep in mind when we're talking about the natural standard state of elements, these this is how they exist in terms of phases and in terms of forms now we also have phosphorus, sulfur and selenium. These don't exist as mono atomic or die atomic atoms. Instead, they're going to exist as poly atomic molecules. Phosphorus exists as P four, sulfur is S eight and selenium and delirium, which are below. It exists as S. E eight and T eight. iodine also is di atomic, it exists as I too. So keep in mind these different forms of the elements in their standard or natural states.