Chapter 3

Electron Affinity

• The energy change that occurs when an electron is acquired by a neutral atom is called that atom's electron affinity
• Electron affinity generally increases across periods
• Increasing nuclear charge along the same sublevel attracts electrons more strongly
• Electron affinity generally increases down groups
• The larger an atom's electron cloud is, the farther away its outer electron are from its nucleus

Ionic Radii

• A positive ion is known as a cation
• The formation of a cation by the loss of one or more electrons always leads to a decrease in atomic radius
• The electron cloud becomes smaller
• The remaining electrons are drawn closer to the nucleus by its unbalanced positive charge
• A negative ion is known as an anion
• The formation of an anion by the addition of one or more electrons always leads to an increase in ionic radius
• Cationic and anionic radii decrease across a period