Hydrogen and ununoctium are two examples of the more than 100 elements that have either been discovered in nature or synthesized by scientists. All of the elements are arranged in the periodic table, which organizes the elements based on atomic mass, number of valence electrons, and physical and chemical characteristics.
The elements are organized into several groups. On the far left of the periodic table are the alkali metals. These elements all have an electric charge of positive one. Some examples include the elements sodium and lithium. Directly to the right of the alkali metals are the alkaline earth metals. All of these elements have a charge of positive two. Magnesium and calcium are both in this group.
On the right side of the periodic table is a group of elements called the noble gases. These elements are unique because they do not react with other elements under natural circumstances. The reason is that the noble gases have a full outer shell of valence electrons and have a neutral charge. Some of these elements are helium, neon, argon and krypton. Next to the noble gases are the halogens, which have a charge of negative one. Fluorine, iodine and bromine fall into this category.
There are also transition metals, which can have varying charges depending on the metal, as well as elements that fall into the actinide and lanthanide series.