What is the primary characteristic of metals on the periodic table?

Metals are characterized by their ability to conduct heat and electricity well, which is a fundamental property that distinguishes them from non-metals and other types of elements on the periodic table. This property arises from the presence of free-moving electrons in metallic bonds, which allow for efficient energy transfer.

In practical terms, metals such as copper and aluminum are widely used in electrical wiring and cookware because of their excellent conductivity. Additionally, metals tend to have a shiny luster, malleability (they can be hammered or pressed into shapes), and ductility (they can be drawn into wires), all of which are related to their ability to conduct energy.

In contrast, other characteristics mentioned in the options help to delineate the properties of metals from non-metals: they are typically malleable rather than brittle, most are solids at room temperature (not gases), and they are not poor conductors; instead, they stand out for their high conductivity. Thus, the ability to conduct heat and electricity well is the primary characteristic that defines metals in the periodic table.