Science, Tech, Math › Science Most Reactive Metal on the Periodic Table Reactivity and the Metal Activity Series Share Flipboard Email Print LYagovy / Getty Images Science Chemistry Periodic Table Basics Chemical Laws Molecules Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated October 08, 2019 The most reactive metal on the periodic table is francium. Francium, however, is a laboratory-produced element and only minute quantities have been made, so for all practical purposes, the most reactive metal is cesium. Cesium reacts explosively with water, though it is predicted francium would react even more vigorously. Using the Metal Activity Series You can use the metal activity series to predict which metal will be the most reactive and to compare the reactivity of different metals. The activity series is a chart that lists elements according to how readily the metals displace H2 in reactions. If you don't have the chart of the activity series handy, you can also use trends in the periodic table to predict the reactivity of a metal or nonmetal. The most reactive metals belong to the alkali metals element group. Reactivity increases as you move down the alkali metals group. The increase in reactivity correlates to a decrease in electronegativity (increase in electropositivity.) So, just by looking at the periodic table, you can predict lithium will be less reactive than sodium, and francium will be more reactive than cesium and all of the other elements listed above it in the element group. What Determines Reactivity? Reactivity is a measure of how likely a chemical species is to participate in a chemical reaction to form chemical bonds. An element that is highly electronegative, such as fluorine, has an extremely high attraction for bonding electrons. Elements at the opposite end of the spectrum, such as highly reactive metals cesium and francium, readily form bonds with electronegative atoms. As you move down a column or group of the periodic table, the size of the atomic radius increases. For the metals, this means the outermost electrons becomes farther away from the positively-charged nucleus. These electrons are easier to remove, so the atoms readily form chemical bonds. In other words, as you increase the size of atoms of metals in a group, their reactivity also increases.