Elements are broadly classified as metals, nonmetals, or metalloids based on their chemical and physical properties. Metals appear on the left and center of the periodic table, nonmetals are on the right, and metalloids form a zig-zag boundary between the two. Understanding the differences between these types of elements helps explain their behavior in chemical reactions, physical states, and real-world applications.
🔑 Key Differences Between Metals and Nonmetals
- Luster: Metals are shiny (lustrous); nonmetals are not shiny and may appear dull or colorful.
- Conductivity: Metals conduct heat and electricity well; nonmetals do not.
- Malleability and Ductility: Metals can be shaped and stretched; nonmetals are brittle.
- State at Room Temperature: Metals are usually solid; nonmetals may be solid, liquid, or gas.
- Ion Formation: Metals form positive ions (cations); nonmetals form negative ions (anions).
- Chemical Nature: Metals tend to lose electrons and form basic oxides; nonmetals gain electrons and form acidic oxides.
- Electronegativity and Ionization Energy: Metals have low values; nonmetals have high values.
| 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 have a 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
Metalloids exhibit a blend of properties from both metals and nonmetals. These elements occur along the “stair-step” line on the periodic table and include elements like boron, silicon, arsenic, and tellurium. In general, metalloids often appear metallic, but are more often 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.
Metalloid Physical Properties
- Appear metallic (lustrous or shiny)
- Brittle like nonmetals (break rather than bend)
- Solid at room temperature
- Intermediate density and melting points (between metals and nonmetals)
- Semiconductors of electricity (conduct better than nonmetals, worse than metals)
- Poor conductors of heat (like nonmetals)
- Not malleable or ductile
- Generally opaque in thin sheets
Metalloid Chemical Properties
- Typically have 3 to 7 electrons in their outer shell
- Can either lose or share electrons in reactions (depending on the element and reaction partner)
- Form amphoteric or weakly acidic/basic oxides
- Exhibit intermediate electronegativity values
- Behave as semiconductors and form alloys with metals
- Often act as catalysts in chemical reactions
❓ Metals vs Nonmetals – Frequently Asked Questions (FAQs)
Q: Is hydrogen a metal, nonmetal, or metalloid?
A: Hydrogen is a special case. It is classified as a nonmetal, but it often behaves like a metal in chemical reactions and under extreme conditions. It forms either a +1 or −1 oxidation state, similar to metals and nonmetals, respectively.
Q: Are metalloids magnetic or conductive like metals?
A: Most metalloids are not magnetic. They conduct electricity, but not as well as metals. Their semiconducting behavior is what makes them important in electronics.
Q: Can a nonmetal ever behave like a metal?
A: Under extreme conditions (e.g., high pressure), some nonmetals like oxygen can exhibit metallic properties. Under normal conditions, they behave as typical nonmetals.
Q: What are some common examples of metalloids?
A: Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), and Tellurium (Te) are examples of metalloids.
Q: Are all metalloids semiconductors?
A: Not all metalloids are semiconductors, but several (especially silicon, germanium, and arsenic) are. Their conductivity can be modified by temperature or doping with other elements.
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.
- Sosa Torres, Martha; Kroneck, Peter M.H. (2021). Metals, Microbes and Minerals: The Biogeochemical Side of Life. Berlin: Walter de Gruyter. doi:10.1515/9783110589771-001
- Tilley, R.J.D. (2004). Understanding Solids: The Science of Materials (4th ed.). John Wiley, New York.