Nonflammable. Not reactive enough to burn in air, even if finely divided.

Metals in this group can react exothermically with oxidizing acids to form noxious gases. Many catalyze polymerization and other reactions, particularly when finely divided. Metals in this group have been known to react with halogenated hydrocarbons, sometimes forming explosive compounds (for example, copper dissolves when heated in carbon tetrachloride). They are less reactive in massive form (sheet, rod, or drop) than when finely divided.

Fumes from the hot metals are toxic by inhalation.

This reactive group includes items (such as certain munitions) that employ less reactive metals or their alloys for housings, supports, tanks, and other structural purposes.

Also included are metals that do not react with air, such as the platinum group metals (platinum, palladium, rhodium, iridium, ruthenium, and osmium), and the coinage metals (copper, silver, and gold). These metals are resistant to corrosion, so they are often used for coinage and jewelry, and they are excellent conductors of electricity, so they are ideal for use in electrical components. Although these metals tend to be unreactive in most situations, they are also known as catalytic metals, especially if finely divided.

Copper, lead, mercury, silver, gold, palladium, platinum.