What is the order of reactivity in the periodic table?

Metals
Period - reactivity decreases as you go from left to right across a period.
Group - reactivity increases as you go down a group
Why? The farther to the left and down the periodic chart you go, the easier it is for electrons to be given or taken away, resulting in higher reactivity.
Non-metals
Period - reactivity increases as you go from the left to the right across a period.
Group - reactivity decreases as you go down the group.
Why? The farther right and up you go on the periodic table, the higher the electronegativity, resulting in a more vigorous exchange of electron.

http://www.tutor-homework.com/Chemistry_Help/electronegativity_table/electronegativity.html

http://www.nelsonthornes.com/secondary/science/scinet/scinet/reaction/react/periodic.htm