Did you know that around 90% of the universe is made up of hydrogen and helium? These two elements are the most abundant in the universe, with hydrogen being the most common. The element with the highest atomic number on the periodic table is Oganesson, with an atomic number of 118. However, this element is synthetic and only exists for a fraction of a second in a lab setting before decaying. The most reactive non-metal on the periodic table is fluorine. It is highly reactive and can even react with noble gases. In its pure form, fluorine is a pale yellow gas. One of the heaviest elements on the periodic table is uranium, with an atomic number of 92. Uranium is commonly used in nuclear reactors and weapons due to its ability to undergo fission. The lightest element on the periodic table is hydrogen. It is the first element in the periodic table and the most abundant element in the universe. Hydrogen is used in a variety of industrial processes, from producing ammonia to processing food. These are just a few interesting facts about the elements on the periodic table. The periodic table is a treasure trove of information about the building blocks of our world.