Periodicity

Atomic radius Ionic radius Ionization energy Electron affinity Electronegativity Metallic character

Atomic radius (Size) One half the distance between the nuclei of identical atoms that are bonded together. Period Decreases across a period Atoms shrink across a period because added protons in the nucleus pull the added electrons more tightly Group Increases down a group Atoms get bigger as you go down the group/ family because orbitals are added to make room for more electrons

Atomic radius

Ionic Radius The trend is the same as atomic radius– size increases down a group and decreases across a period

Ionization Energy Amount of energy required to remove an electron from an atom. Period Increases across a period The outer-most electron becomes more difficult to remove across a period since added protons exert a stronger attraction. Group Decreases down a group The outer-most electron is easier to remove as you move down a column since each time you are one energy level farther from the nucleus

Ionization energy

Electron Affinity The amount of energy released when an atom takes on an electron. Period Increases across a period Group Increases down a group

Electron affinity

Electronegativity The tendency of a bonded atom to attract the electrons in that bond. Period Increases across a period The pull of the increased protons in the nucleus is enough to attract electrons that come close to the outer limits of the atom from other sources. Group Decreases down a group Electrons are more difficult to hold onto as you move down a column.

Electronegativity

Metallic character Period Decreases across a period Metallic properties are most pronounced at the left side of the table where shielding is at a maximum. Group Increases down a group Properties will also increase as you move down a family since shielding improves.

Metallic character Fr (Francium) is the most reactive metal. F (Fluorine) is the most reactive non-metal. The noble gases are very un-reactive.