Trends of the Periodic Table

Trends Trends result from the tug of war between two major forces within the atoms Electron Shielding – the repulsive force caused by electrons ( an electron closer to the nucleus shields electrons further away from the nucleus from feeling the attraction of the nucleus.) Nuclear Attraction – the attraction of negative electrons for the positive nucleus

Triplet Trends Organize trends into triplets Use only increasing properties Learn the diagonal NOT the two vectors that make up the diagonal….. You can always recreate the two vectors so you have less to learn or memorize Learn the members of each triplet and what the increasing diagonal does

Triplet 1: Driven by increasing protons      Atomic Number   m      Atomic Mass      Nuclear Charge

Atomic Number Increases to the right Increases down

Atomic Mass Increases to the right Increases down

Nuclear Charge Increases to the right Increases down

Triplet 2: Driven by increasing electron to electron shielding or repulsion      Atomic Radii Size    Distance between covalent nuclei l      Ionic Radii Size        Overall Activity     

Atomic Radius Is taken as the covalent radius for non-metallic elements and as the metallic radius for metals

Atomic Radius Covalent radius is one-half the distance between the nuclei of two identical atoms that are singly bonded to one another.

Atomic Radius Covalent radii for elements whose atoms do not bond to one another can be estimated by combining radii of those that do with the distances between unlike atoms in various molecules.

Atomic Radius Metallic radius is one-half the closest internuclear distance in a metallic crystal.

Atomic Radius

Atomic Radius

Ionic Radii Size

Overall Activity

Triplet 3: Driven by nuclear attraction for electrons      Ionization Energy Energy required to remove an e- from element in its gaseous form k      Electron Affinity Change in charge when e- captured      Electronegativity Ability to bond & desire for e-

Ionization Energy Is the energy required to remove the outermost electron from an atom or a positive ion in the ground state.

First Ionization Energy Energy required to remove the first electron from a neutral atom.

First Ionization Energy

First Ionization Energy

First Ionization Energy

Second Ionization Energy Energy needed to remove the outermost electron from a +1 ion. Energy needed to remove the second electron from a neutral atom.

Second Ionization Energy

Electron Affinity Energy released or absorbed when an electron is added to the valence level of a gas-phase atom.

Electron Affinity

Electron Affinity

Electronegativity Ability to bond & desire for electrons