Examples of Metallic Compounds, Sorted by Type and Use

A metallic compound is a substance in which one or more metal atoms are chemically bonded to nonmetals, as in rust (Fe2O3) or table salt (NaCl). A pure metal is one element, and an alloy is a mixture of metals. A compound has fixed chemical proportions and properties of its own.

TLDR

• Metallic compounds are metals chemically combined with other elements: oxides, halides, carbonates, sulfates, hydroxides and sulfides are the main families.
• Common examples: Fe2O3, ZnO, TiO2, Al2O3, NaCl, CaCO3, CuSO4, BaSO4, NaOH, Mg(OH)2, ZnS, PbS.
• Brass, steel and bronze are not compounds. They’re alloys.

Table of Contents

• Metallic compounds vs. metals and alloys
• Metal oxides
• Halides
• Carbonates
• Sulfates
• Hydroxides
• Sulfides
• Intermetallic and organometallic compounds
• Properties of metallic compounds
• Quick quiz

Metallic compounds vs. metals and alloys

Three things get mixed up here, and exam questions love to exploit it.

• Pure metal: one element, like iron (Fe) or copper (Cu). Atoms share a sea of free electrons.
• Alloy: a mixture of metals, sometimes with a little carbon. Steel is iron plus carbon. Brass is copper plus zinc. No new chemical formula, and the ratio can vary.
• Metallic compound: a metal chemically bonded to another element in a fixed ratio. Iron(III) oxide is always two iron atoms to three oxygens.

Most of the compounds below are also ionic compounds: the metal gives up electrons and the nonmetal takes them. “Metallic compound” is the textbook shorthand for any compound containing a metal, so ionic compounds containing metals are the largest group inside it.

Metal oxides

Metal oxides form when a metal combines with oxygen. They’re the biggest family, and many of them are pigments or ceramics.

Name	Formula	Everyday use
Iron(III) oxide	Fe2O3	Rust; red pigment in paint and bricks
Zinc oxide	ZnO	Sunscreen, diaper cream
Titanium dioxide	TiO2	White pigment in paint, paper and toothpaste
Aluminum oxide	Al2O3	Sandpaper abrasive; rubies and sapphires are gem-quality crystals of it
Magnesium oxide	MgO	Furnace linings, dietary supplements
Calcium oxide	CaO	Quicklime for cement and steelmaking

Rust is the example you’ve actually seen. Iron reacts with oxygen and water, and the flaky orange-brown result is mostly hydrated iron(III) oxide.

Halides

Halides combine a metal with fluorine, chlorine, bromine or iodine.

Name	Formula	Everyday use
Sodium chloride	NaCl	Table salt, road de-icing
Calcium fluoride	CaF2	Mineral fluorite; lenses and optics
Silver chloride	AgCl	Photographic film and paper
Potassium iodide	KI	Iodized salt, thyroid protection

Sodium chloride is the standard classroom example of an ionic lattice: each Na+ is surrounded by six Cl- ions, and vice versa.

Carbonates

Carbonates contain the CO3 group bonded to a metal. They fizz when acid hits them.

Name	Formula	Everyday use
Calcium carbonate	CaCO3	Limestone, chalk, marble, seashells, antacid tablets
Sodium carbonate	Na2CO3	Washing soda, glass making
Sodium bicarbonate	NaHCO3	Baking soda
Copper carbonate	CuCO3	Green patina component, pigments

Calcium carbonate shows up in both a cliff face and the tablet you take for heartburn. Same compound, very different scale.

Sulfates

Sulfates pair a metal with the SO4 group.

Name	Formula	Everyday use
Copper(II) sulfate	CuSO4	Blue crystals; garden fungicide, school demonstrations
Barium sulfate	BaSO4	The “barium meal” that makes the digestive tract visible on X-rays
Calcium sulfate	CaSO4	Gypsum, plaster, drywall
Magnesium sulfate	MgSO4	Epsom salt

Barium ions are toxic, yet barium sulfate is safe to swallow because it barely dissolves. PubChem’s entry on barium sulfate covers its medical use.

Hydroxides

Hydroxides contain the OH group bonded to a metal. Many are bases.

Name	Formula	Everyday use
Sodium hydroxide	NaOH	Lye for soap making and drain cleaner
Magnesium hydroxide	Mg(OH)2	Milk of magnesia, antacid
Calcium hydroxide	Ca(OH)2	Slaked lime for mortar and soil treatment
Potassium hydroxide	KOH	Alkaline batteries, liquid soaps

Sulfides

Sulfides combine a metal with sulfur. Many are ores.

Name	Formula	Everyday use
Zinc sulfide	ZnS	Glow-in-the-dark coatings, phosphors
Lead(II) sulfide	PbS	Galena, the main lead ore; early radio crystal detectors
Iron(II) sulfide	FeS	Lab source of hydrogen sulfide
Iron disulfide	FeS2	Pyrite, “fool’s gold”

Intermetallic and organometallic compounds

Two edge cases are worth knowing because they blur the line.

• Intermetallic compounds combine two or more metals in a fixed ratio with an ordered crystal structure, unlike a random alloy. Ni3Al strengthens jet engine turbine blades, and Nb3Sn is used in superconducting magnets.
• Organometallic compounds have a bond between a metal and carbon. Ferrocene, Fe(C5H5)2, is a metal sandwiched between two carbon rings. Chlorophyll’s magnesium-centered ring is a related biological case.

Lithium cobalt oxide (LiCoO2), common in phone and laptop battery cathodes, is a metal oxide you probably have within arm’s reach.

Properties of metallic compounds

The properties differ sharply from those of the metals inside them.

• Brittle, not malleable. Hit a salt crystal with a hammer and it shatters. Hit copper and it dents.
• High melting points. NaCl melts at about 801 °C, far above where most plastics fail.
• Conduct when molten or dissolved, not as solids, because ions can’t move in the lattice.
• Often colored. Copper sulfate is blue, iron(III) oxide is red, and many transition metal compounds are vivid. Pure metals are mostly silvery.
• Different reactivity. Sodium metal explodes in water; sodium chloride sits happily in a shaker.

Quick quiz

1. Is brass a metallic compound? No. It’s an alloy of copper and zinc.
2. What is the formula for rust? Fe2O3 (hydrated in practice).
3. Which is a metallic compound: Fe, steel or FeS? FeS.
4. Name the metal in Epsom salt (MgSO4). Magnesium.
5. Is CO2 a metallic compound? No. It has no metal.