Nonmetals share a number of common properties, though there are some exceptions:

Physical Properties:

* Poor conductors of heat and electricity: This is a defining characteristic. Nonmetals, like rubber or wood, are excellent insulators.

* Brittle: They tend to break easily when subjected to force.

* Dull appearance: They lack the luster of metals, often appearing dull or earthy.

* Gases or solids at room temperature: Most nonmetals are gases (like oxygen, nitrogen, and chlorine) at room temperature, with a few being solids (like sulfur and phosphorus). Only one nonmetal, bromine, is a liquid at room temperature.

Chemical Properties:

* High ionization energy: They tend to gain electrons, making them good oxidizing agents.

* High electronegativity: They attract electrons strongly.

* Form acidic oxides: Nonmetal oxides, like sulfur dioxide (SO₂) or carbon dioxide (CO₂), react with water to form acidic solutions.

* React with metals to form salts: For example, chlorine reacts with sodium to form sodium chloride (NaCl).

Exceptions:

It's important to note that not all nonmetals share every property. Some exceptions include:

* Carbon: While generally considered a nonmetal, carbon exists in various forms (diamond, graphite, etc.) with varying properties, including conductivity.

* Astatine: This radioactive nonmetal is a liquid at room temperature, which is unusual for nonmetals.

Overall: Nonmetals are a diverse group of elements with a range of properties. However, they generally lack the luster, conductivity, and malleability of metals and tend to be brittle, have high ionization energy, and form acidic oxides.