Transcript Periodicity
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 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.