Formation of Anions

When atoms of nonmetallic elements gain electrons, they become anions. For example, when chlorine gains an electron, it forms the chloride anion (Cl-). The extra electron gives the chloride ion a negative charge.

Naming Anions

Anions are named by adding the suffix "-ide" to the root of the element's name. For example, the anion formed from oxygen is called oxide (O2-), and the anion formed from sulfur is called sulfide (S2-).

Properties of Anions

Anions tend to be larger than the corresponding neutral atoms, as they have gained one or more electrons, leading to increased repulsion among the electrons, causing the outer electron shell to expand. Anions are also attracted to the positive terminal (anode) of an electrical field due to their negative charge.

Study Guide for Anions

1. What is an anion?
2. How are anions formed?
3. Give an example of an anion and its formation.
4. How are anions named?
5. Compare the size of anions with their corresponding neutral atoms.
6. Explain the electrical attraction of anions in an electrical field.

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