ammonium

American  

[uh-moh-nee-uhm] / əˈmoʊ ni əm /

noun

Chemistry.

1. the univalent ion, NH 4 + , or group, NH 4 , which plays the part of a metal in the salt formed when ammonia reacts with an acid.

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ammonium British  

/ əˈməʊnɪəm, -njəm /

noun

1. (modifier) of, consisting of, or containing the monovalent group NH 4 – or the ion NH 4 ⁺

   ammonium compounds

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ammonium Scientific  

/ ə-mō′nē-əm /

1. A positively charged ion, NH ₄, derived from ammonia and found in a wide variety of organic and inorganic compounds. Compounds of ammonium chemically resemble the alkali metals.

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Etymology

Origin of ammonium

< New Latin; see ammonia, -ium; coined by J. J. Berzelius in 1808

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Compare meaning

How does ammonium compare to similar and commonly confused words? Explore the most common comparisons:

• ammonia vs. ammonium

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Explanation

Ammonium is a positively charged polyatomic ion made of nitrogen and hydrogen, commonly found in fertilizers and in compounds used in some household disinfectants. Ammonium is composed of one nitrogen atom bonded to four hydrogen atoms, carrying a net positive charge. It forms when ammonia (a nitrogen atom bonded to three hydrogen atoms) accepts a hydrogen proton. Ammonium can bond with negatively charged ions to form salts. Some ammonium salts, such as ammonium nitrate, are used in fertilizers to provide nitrogen that helps plants grow. Certain other ammonium-containing compounds are used in cleaning products as disinfectants to kill germs and bacteria.

Example Sentences

See Examples For:

ammonium

In 2024 China accounted for 70% of Russia’s imports of ammonium perchlorate, an essential ingredient in ballistic-missile fuel.

From The Wall Street Journal ● Dec. 18, 2025

Growing even modest quantities of mycoprotein requires significant inputs, and the spores must be cultivated in large metal tanks filled with sugar-rich feedstock and added nutrients such as ammonium sulfate.

From Science Daily ● Nov. 21, 2025

Davis said six packages of ammonium nitrate were shipped from Park in Seattle to Bartkus.

From Los Angeles Times ● Jun. 24, 2025

Distillers threw rotten fruit and molasses waste in the gallon to brew with ammonium chloride to produce something called “snake juice,” which was collected by lepers and taken around the city.

From Salon ● Feb. 2, 2025

Ed McMillan had staged the Rad Lab’s most determined search for the isotope by propping a bottle of granular ammonium nitrate in the path of the thirty-seven-inch machine’s neutron beam for several months.

From "Big Science" by Michael Hiltzik

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