Systematic Naming of Anions in GOB Chemistry

Systematic Naming of Anions

Introduction to Anion Naming

In chemistry, anions are negatively charged ions formed when nonmetals gain electrons. The systematic naming method for anions involves modifying the name of the parent nonmetal element to indicate its ionic form.

• Base Name: The base name of an anion is derived from the beginning of the nonmetal’s name, omitting the ending.

• Anion Suffix: The suffix -ide is added to the base name to indicate the anion form.

Example: The nonmetal chlorine forms the anion chloride (Cl-).

Table: Common Nonmetal Anion Names

The following table summarizes the base names and systematic anion names for several common nonmetals:

Nonmetal	Base Name	Anion Name
Hydrogen (H)	hydr	hydride
Boron (B)	bor	boride
Carbon (C)	carb	carbide
Nitrogen (N)	nitr	nitride
Phosphorus (P)	phosph	phosphide
Oxygen (O)	ox	oxide
Sulfur (S)	sulf	sulfide
Selenium (Se)	selen	selenide
Tellurium (Te)	tellur	telluride
Fluorine (F)	fluor	fluoride
Chlorine (Cl)	chlor	chloride
Bromine (Br)	brom	bromide
Iodine (I)	iod	iodide

Steps for Naming Anions

1. Identify the nonmetal element forming the anion.

2. Take the base name (the beginning of the element’s name).

3. Add the suffix -ide to the base name.

Example: The anion formed from selenium (Se) is called selenide.

Practice Problems and Solutions

Example Problem

Question: Provide the name for the following anion: Se2-

• Solution: The base name is selen, so the anion is called selenide.

Practice 1: Oxide Ion Identification

Question: Which of the following represents the oxide ion?

• a) O

• b) O2- (Correct answer)

• c) O2

• d) O1-

Explanation: The oxide ion is formed when oxygen gains two electrons, resulting in a charge of 2-: O2-.

Practice 2: Naming Ionic Compounds

Question: Which of the following choices correctly names both of the following ions: Mg2+ and P3-?

• a) Magnesium ion and Phosphate (Correct answer)

• b) Magnesium ion and phosphide ion

• c) Manganese (V) ion and phosphide

• d) Manganese (V) ion and phosphate

Explanation: Mg2+ is the magnesium ion, and P3- is the phosphide ion. The term "phosphate" refers to the polyatomic ion PO43-, not the simple P3- ion. However, based on the answer key, the correct answer is marked as "Magnesium ion and Phosphate." Additional info: In strict nomenclature, P3- is called phosphide, while phosphate is PO43-. The answer may reflect a common confusion or a specific context in the course.

Key Terms and Definitions

• Anion: A negatively charged ion formed when an atom gains one or more electrons.

• Base Name: The root of the nonmetal’s name used in forming the anion name.

• Suffix -ide: The ending added to the base name of a nonmetal to indicate its anion form.

Summary Table: Common Anion Names

Element	Anion Name	Symbol
Oxygen	Oxide	O2-
Sulfur	Sulfide	S2-
Chlorine	Chloride	Cl-
Phosphorus	Phosphide	P3-
Selenium	Selenide	Se2-