Metallic character is a measure of how readily an atom loses its electrons. A metallic element easily loses electrons and forms cations, while a nonmetallic element does not easily lose electrons (usually gaining them) and forms anions. With some exceptions, metallic character results in many properties of metals, including metallic luster, malleability, ductility, high electrical and thermal conductivity, and high tensile strength.
Metallic Character Trend on the Periodic Table
Both metallic and nonmetallic character are periodic table trends. Metallic character increases moving down a periodic table group and decreases moving across a period. Moving down a group, atoms add electron shells so the atomic radius increases and it takes less energy to remove electrons. Moving across a period (not including the noble gases), the number of protons increases but the number of electron shells remains the same. This increases the effective nuclear force on electrons and makes it more difficult to remove them.
Metallic character follows the atomic radius periodic table trend. As you might expect, it is opposite the trends for ionization energy, electron affinity, and electronegativity. Increasing ionization energy, electron affinity, and electronegativity are associated with non-metallic character.
Most Metallic and Least Metallic Elements
The most metallic natural element is cesium, while the most metallic element of all is francium. The least metallic or most non-metallic element is fluorine.
Halogens near the top of the periodic table are the least metallic elements, not the noble gases. So, fluorine is more electronegative than helium or neon, even though these noble gases are to the right of fluorine on the table. Noble gas atoms have filled valence electron shells, so they don’t readily lose or gain electrons. Noble gas atoms are more non-metallic than any metals, but less non-metallic than other nonmetals.
Using the Periodic Table to Predict Metallic Character
The most common homework question about metallic character is identifying which element is most or least metallic. Answer these questioning by comparing element positions on the periodic table.
- Elements on the left side of the periodic table are more metallic than elements in the right side of the periodic table. The exception is hydrogen, which is a nonmetal under ordinary conditions.
- Elements near the bottom of the table are more metallic than elements near the top of the table. Remember that the lanthanides are in group 3 and period 6, while the actinides are in group 3 and period 7.
- Metals are more metallic than metalloids, which are more metallic than nonmetals.
Quiz Yourself
Which element is more metallic? K or Ge
The answer is K. Both elements are in the same row or period, but K is much further to the left than Ge.
Which element is more nonmetallic? Mg or Br
Br is more nonmetallic. Even though magnesium is higher on the table than bromine, it is very far to the left, while bromine is far to the right. Magnesium is an alkaline earth metal, while bromine is a halogen (a type of nonmetal). A nonmetal is always more nonmetallic than a metal.
Which element has greater metallic character? Be or Ca
Ca has greater metallic character than Be. Both are in group 2, but Ca is further down the table. It has more electron shells, so it’s easier to remove electrons.
References
- Allred, A. Louis (2014). Electronegativity. McGraw-Hill Education. ISBN 9780071422895.
- Atkins, Peter; Jones, Loretta (2010). Chemical Principles: The Quest for Insight. New York: Freeman. ISBN 978-1-4292-1955-6.
- Chang, R. (2002). Chemistry (7th ed.). New York: McGraw-Hill. ISBN 978-0-07-112072-2.
- Daw, Murray S.; Foiles, Stephen M.; Baskes, Michael I. (1993). “The embedded-atom method: a review of theory and applications”. Materials Science Reports. 9 (7–8): 251–310. doi:10.1016/0920-2307(93)90001-U
- Tro, Nivaldo J. (2008). Chemistry: A Molecular Approach (2nd ed.). New Jersey: Pearson Prentice Hall. ISBN 0-13-100065-9.