Metals, Nonmetals, and Metalloids on the Periodic Table: A Guide

Most elements are metals. They occupy the left and center of the periodic table, while nonmetals cluster in the upper right. Metalloids lie along the staircase-shaped boundary between them. An element’s position offers a first clue about its properties, though these categories describe general patterns, not guarantees.

Metals

Metals make up most of the periodic table. They include the elements on the left and center, as well as the lanthanides and actinides shown in the two rows below the main table.

Metals generally conduct heat and electricity well. Many are shiny, and solid metals can often be shaped without breaking. The ability to flatten a metal is called malleability; the ability to draw it into wire is called ductility. In chemical reactions, metal atoms often lose electrons and form positive ions.

Metal properties vary. Some metals are soft and reactive; others are harder or less reactive. The label “metal” describes broad tendencies, not a single behavior shared equally by every element.

Nonmetals

Most nonmetals sit in the upper-right part of the table. Hydrogen is a nonmetal placed at the top left, apart from the main cluster. Carbon, nitrogen, oxygen, the halogens, and the noble gases are among the nonmetals.

Nonmetals usually conduct heat and electricity poorly. Solid nonmetals tend to be brittle, and many are gases at room temperature. In reactions, nonmetals may gain electrons to form negative ions. They also commonly share electrons with other atoms to form covalent bonds.

These tendencies have exceptions. Graphite, a form of carbon, conducts electricity, even though carbon is classified as a nonmetal. The categories help predict likely properties, but not every element fits every description.

Metalloids

Metalloids lie along the staircase boundary between metals and nonmetals. The elements commonly classified as metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium, according to the Encyclopaedia Britannica entry on metalloids. Classifications can differ at the edges; some sources also include polonium or astatine.

Metalloids have a mix of metallic and nonmetallic traits. Many conduct electricity less effectively than metals, and some are semiconductors. A semiconductor conducts electricity under some conditions, but not as freely as a good conductor such as copper. Silicon is a familiar example. Metalloids can also show varied chemical behavior, so their position on the table offers a starting point for understanding them, not a complete prediction.

The staircase is a visual guide, not a formal dividing line that settles every classification. The IUPAC periodic table provides the element layout; the exact boundary between the categories depends on how a source defines “metalloid.”

Example: classifying silicon

Silicon sits below carbon and to the left of phosphorus, on the staircase boundary. Its position suggests that it is a metalloid. Its electrical behavior supports that classification: silicon is a semiconductor, with conductivity between that of an insulator and a good metal such as copper. Its location and properties make it a clear example of a metalloid.

How to read the pattern

As you move from left to right across a row, elements generally change from metallic to nonmetallic in character. Period 3 shows this pattern: sodium and magnesium are metals, silicon is a metalloid, and phosphorus, sulfur, chlorine, and argon are nonmetals. The change is linked to how strongly atoms attract their outer electrons. Across a period, that attraction generally increases, so atoms become less likely to give electrons away.

A similar broad pattern appears down some groups. Atoms get larger, and their outer electrons are farther from the nucleus. In group 14, carbon is a nonmetal, silicon and germanium are commonly classified as metalloids, and tin and lead are metals. This trend helps explain the shift, but checking an element’s properties is still necessary.

Key Takeaways

• Metals occupy most of the left and center of the periodic table. Nonmetals cluster in the upper right, with hydrogen at the top left.
• Metalloids lie along the staircase boundary. Boron, silicon, germanium, arsenic, antimony, and tellurium are commonly included.
• Metals generally conduct well and tend to lose electrons. Nonmetals usually conduct poorly and may gain or share electrons.
• Metalloids have mixed properties; some are semiconductors.
• An element’s location is a useful first clue, but individual properties and classification conventions matter.