Elements may be classified as metals, nonmetals, or metalloids. Elements with some characteristics of metals and some of nonmetals are metalloids. Metals are on the left side of the periodic table. Nonmetals are on the right side of the table. Metalloids occur in zig-zag line on the table, separating metals and nonmetals. Here is a look at the difference between metals and nonmetals.
| Metals | Nonmetals |
| Metallic luster (shiny) | Not lustrous |
| Good conductors of heat and electricity | Poor conductors of heat and electricity |
| Malleable – can be beaten into sheets | Brittle solids |
| Ductile – can be stretched into wire | Nonductile |
| Opaque thin sheets | Transparent thin sheets |
| Sonorous (bell sound when struck) | Not sonorous |
| Usually solid at room temperature | Solid, liquid, or gas at room temperature |
| Form cations (positive-charged ions) | Form anions (negative-charged ions) |
| Usually 1-3 electrons in outer shell | Usually 4-8 electrons in outer shell |
| Form basic oxides | Form acidic oxides |
| Good reducing agents | Good oxidizing agents |
| Low electronegativity | High electronegativity |
| Low ionization energy | High ionization energy |
| Mostly high melting points | Low melting points |
| Intermediate to large atomic radius | Small to intermediate atomic radius |
Metals
About 75% of elements on the periodic table are metals. Because so many elements are metals, they are subdivided into smaller groups, including the alkali metals, alkaline earth metals, transition metals, post-transition or basic metals, lanthanides, and actinides. Most metals are easy to recognize by their shiny, metallic appearance. But, they share other properties in common with each other. One common property is metallic character, which means atoms of metals readily lose electrons.
Metal Physical Properties
- Lustrous (shiny)
- Good conductors of heat and electricity
- High melting point
- High density (heavy for their size)
- Malleable (can be hammered)
- Ductile (can be drawn into wires)
- Usually solid at room temperature (an exception is mercury)
- Opaque as a thin sheet (can’t see through metals)
- Metals are sonorous or make a bell-like sound when struck
Metal Chemical Properties
- Have 1-3 electrons in the outer shell of each metal atom and lose electrons readily
- Corrode easily (e.g., damaged by oxidation such as tarnish or rust)
- Lose electrons easily
- Form oxides that are basic
- Have low electronegativity values
- Are good reducing agents
Nonmetals
Nonmetals include the nonmetal, halogen, and noble gas groups on the periodic table. While most metals are solid at room temperature, there nonmetallic solids, liquids, and gases. The nonmetals are a diverse collection of elements, but they share some common properties.
Nonmetal Physical Properties
- Not lustrous (dull appearance, sometimes colorless)
- Poor conductors of heat and electricity
- Nonductile solids
- Brittle solids
- May be solids, liquids or gases at room temperature
- Transparent as a thin sheet
- Nonmetals are not sonorous
Nonmetal Chemical Properties
- Usually have 4-8 electrons in their outer shell
- Readily gain or share valence electrons
- Form oxides that are acidic
- Have higher electronegativities
- Are good oxidizing agents
Metalloids
It’s helpful to know the difference between metals and nonmetals in order to identify metalloids. Metalloids have some properties of metals and some properties of nonmetals. In general, metalloids often appear metallic, but are more likely to be semiconductors than conductors. Like nonmetals, metalloids are neither malleable nor ductile. While solid at room temperature, metalloids have lower melting points than most metals. Metalloids have electronegativity values intermediate between metals and nonmetals.
References
- Askeland, D.R.; Fulay, P.P.; Wright, J.W. (2011). The Science and Engineering of Materials (6th ed.). Cengage Learning, Stamford, CT. ISBN 0-495-66802-8.
- Lide, D.R.; Frederikse, H.P.R. (eds.) (1998). CRC Handbook of Chemistry and Physics (79th ed.). CRC Press, Boca Raton, Florida. ISBN 0-849-30479-2.
- Tilley, R.J.D. (2004). Understanding Solids: The Science of Materials (4th ed.). John Wiley, New York.