-ide and -ate, how do you know which one to use?

1 Answer
Nov 8, 2015

Answer:

-ide: used when the anion is monoatomic.
-ate: used when the anion is polyatomic (but still depends on the oxidation state of the ion)

Explanation:

In naming ionic compounds, the name of the metal cation (positively charged) usually goes first followed by the name of the nonmetal anion (negatively charged).

The suffix -ide is only used if the nonmetal anion is monoatomic (meaning one atom).

e.g. chloride (#Cl^"1-"#); bromide (#Br^"1-"#); iodide (#I^"1-"#); fluoride (#F^"1-"#); hydride (#H^"1-"#); oxide (#O^"2-"#)

Notable exceptions to the above rule are the hydroxide (#OH^"-1"#) and cyanide (#CN^"1-"#) ions as they were assumed to be monoatomic ions when they were first discovered.

The use of the suffix -ate, on the other hand, is not that simple. The metal anion must be (1) polyatomic (meaning many atoms) and (2) must satisfy the required oxidation state.

http://mrkubuske.com/tag/ions/

As seen in the image above suggests, the use of the suffix -ate versus the use of the suffix -ite is self-evident.