Periodicity

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 tightlyGroup• 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 characterPeriod•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.