The periodic table is most likely the key tool for chemists.  It organizes the elements, but it also gives a wealth of information.

Key sections of the periodic table
The periodic table is organized in columns, called groups or families, and rows, called periods.  There are several groups or periods that have specific names.
Important Regions of the Periodic Table:

8 tall columns = main groups or representative elements

Periodicity
As you move across or down the periodic table, subatomic particles are added.  This increases the mass of the elements both across and down the periodic table.

Moving across the periodic table, protons are added to the nucleus while electrons are added to the valence shell.  This increase in both the number of positive charges and negative charges increases the attraction between the two.  Therefore, when moving across the periodic table, the radius decreases.  When moving down the periodic table, protons are again added.  But this time, the electrons are added in a completely new valence shell.  This new valence shell is shielded from the pull of the protons by all the inner valence shells.  Therefore, as you move down the periodic table, atomic radius increases.

Electron affinity (the ease with which an electron is added), electronegativity (pull an electron has on electrons it shares in a bond) and ionization energy (difficulty in removing the outermost electron) are all related to the radius.  As radius decreases across the periodic table, all of these properties increase as the electrons are closer to the pull of the protons.  As radius increases down a group, these properties decrease as the electrons are farther from the nucleus.

Ionic Radii
The formation of a cation is due to the loss of electrons.  A cation has more protons than electrons and therefore the protons have a large pull on each electron.  The radius decreases.  An anion is formed from the gain of electrons.  Anions have a greater number of electrons than protons.  Therefore, the pull of the protons on each electron is lower.  The radius of an anion is greater than the parent atom.

The periodic table is the main tool chemists use to organize the elements.  There are many trends in properties that appear on the periodic table.  This tutorial introduces the main sections of the periodic table and explains the trends in properties that occur throughout the table.

Specific Tutorial Features:

• The trends aren’t just given…they are explained in terms of one another and linked together
• Mnemonic is given for easy memorizing of 1st 20 elements
• Animations of the periodic table
• Visual representation of trends of the periodic table 

Series Features:

• Concept map showing inter-connections of new concepts in this tutorial and those previously introduced.
• Definition slides introduce terms as they are needed.
• Visual representation of concepts
• Animated examples—worked out step by step
• A concise summary is given at the conclusion of the tutorial.

• Periodic table
  • Key sections of the periodic table
  • Mnemonic for memorizing 1st 20 elements
• Periodicity
  • Atomic mass
  • Atomic radii
  • Electronegativity
  • Electron affinity
  • Ionization energy
• Ionic Radii