The most reactive metal in the periodic table is francium. Francium belongs to the alkali metals, a group on the periodic table whose members are all highly reactive. These metals are highly reactive because they all have only one valence electron.
The most reactive metals found on the periodic table are the alkali metals, which are lithium, sodium, potassium, rubidium, caesium and francium. The alkali metals are found on the periodic table's s-block, because the outermost electron in these elements is in an s-orbital.
The most reactive non-metal is fluorine, and it is also the most reactive element that scientists have discovered. Fluorine combines readily with almost any substance, including metals that are usually stable.
Neon is the least reactive element on the periodic table. As a noble gas, neon is colorless and odorless with extremely low reactivity in its natural state. Neon has an atomic number of 10.
A metal atom's aptitude to lose electrons to other atoms causes it to be more reactive. Involved in the scientifically determined aptitude is the speed at which a metal atom can lose electrons, as well as the substances with which the atom is likely to react.
The most reactive group of metals on the periodic table are the alkali metals. These metals are so reactive that they are not found naturally by themselves; they are found in nature as parts of compounds.
The reactivity of a metal is determined by how tightly the metal holds onto the electrons in its outermost energy level. These electrons are called valence electrons. Metals usually have fewer valence electrons than nonmetals.
As of 2014, there are 84 metal elements on the Periodic Table of Elements, four of which are unnamed at this time. Metals are one of three classifications of the elements: there are metals, nonmetals and metalloids. Named and unnamed elements are being added as more substances are discovered.
The reactivity trend of the halogens is that the higher up on the Group VIIa column the halogen is, the more reactive it is. Therefore, the most reactive halogen is fluorine, while the least reactive, non-radioactive halogen is iodine.
Elements become denser toward the bottom of the periodic table. From left to right on the table, elements become denser toward the center of the table and less dense on either end.